Atoms and Elements - Weebly€¦ · What are the symbols of the first 20 elements and other common ones? What symbols and systems help people use chemicals safely at home, work and

Mr. Storie 10S Science FINAL EXAM REVIEW

**THIS IS NOT A COMPLETE REVIEW. READ ALL COURSE NOTES, GO THROUGH THE

WORKBOOK, HANDOUTS, QUIZZES, and know all VOCABULARY **

• Start at least 1 week before exam

• Break the material into sections

• Take a study break every 20-30 min

• Plan ahead to lower anxiety on the day of the exam

• Look at quizzes/tests to pick which topics to focus on

• If you are stuck, highlight the question and ASK later

Atoms and Elements

Essential Outcomes

√ Place a check mark next to the question when you feel you have it down

What are the symbols of the first 20 elements and other common ones?

What symbols and systems help people use chemicals safely at home, work and for the environment?

How do you classify matter using the words: element, compound, atom, molecule, mixture and pure?

What properties classify elements as metals, non-metals or metalloids?

How do you identify physical and chemical change and if a chemical reaction has taken place?

1. Give the following elemental symbols or names:

Calcium - Fluorine - Neon - Copper - Tin -

Mg - Li Au Ag Al

2. Match the WHMIS symbols to their meanings:

a.

_____ 1. Biohazardous infectious material.

b.

_____ 2. Corrosive material.

c.

_____ 3. Material causing immediate and serious toxic effects.

d.

_____ 4. Flammable and combustible material.

e.

_____ 5. Irritating and allergic material.

3. What is the difference between WHMIS and HHPS and what does each involve?


4. Briefly define each term and give an example of each:

a) An element:

b) An atom:

c) A compound:

d) A molecule:

e) A homogenous mixture:

f) A heterogeneous mixture:

g) A metalloid

5. Explain what these properties describe for metals and nonmetals (if possible).

a) Lustre:

b) Malleability:

c) Ductility:

d) Viscosity:

e) Solubility:

f) Combustible:

6. Give an example and explain the difference between a physical property and a chemical property.


7. Give an example and explain the difference between a physical change and a chemical change.

8. What happens in a chemical reaction?

9. What are some of the signs that a chemical reaction has taken place?

10. Indicate whether each of the following is a physical or a chemical change. Explain:

a) Water boiling in a kettle. ________________________________________________

b) Fireworks exploding in the sky ________________________________________________

c) Sugar dissolving in water. ________________________________________________

d) Pennies added to Nitric acid. ________________________________________________

Extension Outcomes


What is the basic subatomic structure of an atom?

How do you use atomic number and atomic mass to identify parts of the atom?

How do you draw an atom using a Bohr Diagram?

How is the Periodic Table organized for the elements and what patterns exist?

11. What is a subatomic particle? Give some information about them.

12. Which of the following best describes atoms?

a) Nucleus contains electrons and neutrons; nucleus is surrounded by protons

b) Nucleus contains neutrons; nucleus is surrounded by protons and electrons Nucleus contains protons

and electrons; nucleus is surrounded by neutrons

c) Nucleus contains protons and neutrons; nucleus is surrounded by electrons


13. The number of protons in an atom can be determined from the ________________.

14. How do you find the number of neutrons?

15. Complete this table: *Note that the mass is for any particular atom – could be an isotope.

Proton # Electron # Neutron # At. Mass At. # Element Symbol

Neon

7

13

15

8 C

16. How many valence electrons are in the outer orbit of sodium, a member of the alkali metals?

17. How many electrons are allowed to a maximum in each orbit?

18. Draw a complete Bohr model for sodium.

Chemical symbol:______ Atomic #:______ p+:____ no:____ e-:____

19. Use a periodic table to identify these elements.

a) Metal in period 5, group 11 _________

b) Element with atomic mass 16.0 amu _________

c) Metalloid in the second period _________

d) Metal in period 3 that would most likely have an ion charge of +3 _________

e) Halogen with atoms heavier than sulphur’s and an atomic number less than selenium _________


20. Label the 5 chemical families: Alkali Metals, Alkaline Earth Metals, Chalcogens, Halogens, Noble gases.

21. What is the definition of a chemical family?

22. What is meant by the term “group” in the periodic table?

a) A collection of elements in the same period

b) A collection of elements that are all solids

c) A column of elements with similar properties

d) A horizontal row of elements

Exploration Outcomes

Why do families react differently during chemical reactions?

How do you use a formula to find the elements in the molecule and the number of atoms of each element?

How did each person contribute to our understanding of matter?

23. What is the charge on calcium when it forms an ion?

24. What is the charge that results when a halogen forms an ion?

25. What family is the most unreactive? Why?


26. Draw and label a Sulphur ion.

Chemical symbol:______ Atomic #:______ p+:____ no:____ e-:____

27. Given the following formulas, how many of each element is in a molecule of that substance?

a) H2O __________________________________________________________

b) 3 C3H8 __________________________________________________________

c) 2 Mg3(PO4)2 __________________________________________________________

28. Show with an example the difference between a subscript and a coefficient.

29. Explain the atomic model developed by these men.

a. Bohr

b. Rutherford

c. Dalton

d. Thomson


Reproduction

Essential Outcomes


How are the terms DNA, chromosome, genes, and trait connected?

Why do cells divide and how does it work?

What role do gametes play in reproduction?

What parts make up the male and female sex systems and what is the function of each part?

30. Which of the following is a trait?

a) Age b) Eye colour

c) Name d) Number of siblings

31. What does DNA do when a cell is ready to divide?

a) Divides into 46 parts b) Divides into two parts

c) Folds up into a chromosome d) Unfolds into a gene

32. What must happen in a nucleus before it can undergo mitosis?

a) Grow b) Double

c) Change colour d) Disappear

33. What occurs during interphase?

a) Chromosomes pair up at the centre of the cell.

b) The cell grows and DNA and organelles are duplicated.

c) The cell rests.

d) The cell splits into two separate cells.

34. Which of the following is the correct order of the three stages of the cell cycle?

a) cytokinesis, replication, interphase

b) interphase, cytokinesis, mitosis

c) interphase, mitosis, cytokinesis

d) interphase, replication, cytokinesis

35. This question refers to Figure 1 below. The correct sequence of events in mitosis

a) 1, 2, 3, 4, 5 b) 2, 3, 1, 4, 5

c) 5, 4, 3, 2, 1

d) 4, 3, 2, 5, 1


36. Which of the following is only true for mitosis?

a) Cells divide twice b) Gamete cells are produced

c) Genetically different cells are made d) Genetically identical cells are made

37. Mitosis occurs in ______.

a) Plants b) Humans

c) Monkeys d) All of the above.

38. Meiosis occurs in _____.

a) Plants b) Humans

c) Monkeys d) All of the above.

39. Diploid cells have ______.

a) 23 pairs of chromosomes b) 46 pairs of chromosomes

c) 23 chromosomes

d) A and B are correct

40. Asexual reproduction does not occur in…

a) Plants b) Starfish

c) Bacteria d) Rabbits

41. Asexual reproduction provides for…

a) Lots of variation b) Lots of evolution

c) Little variation d) Zero variation

42. Which of the following is the correct order in sexual reproduction?

a) fertilization, meiosis, gamete, zygote

b) gamete, fertilization, meiosis, zygote

c) gamete, meiosis, fertilization, zygote

d) meiosis, gamete, fertilization, zygote

43. In any oocyte cell, the sex chromosomes is/are .

a) X b) XY

c) XX

d) Y

44. Which of the following is the biggest disadvantage of asexual reproduction?

a) Less energy is required b) Produces many offspring

c) Colonies are produced quickly

d) Offspring are genetic clones

45. What is the main advantage of sexual reproduction?

a) Fewer offspring are produced.

b) The embryo is protected from dehydration.

c) The offspring are genetically different from the parents.

d) Very little energy is required to find a mate.


46. Label what parts you can of the following reproductive systems diagrams.

d._________________

e._________________

f._________________

g._________________

h._________________

i._________________

j._________________

k._________________

a._________________

b._________________

c._________________

a.________________

b.________________

c.________________

d.__________________

e.___________________

f.________________

g.________________

h.________________


Extension Outcomes

How does a fertilized egg turn into a baby and what determines the gender?

How are the features of the parents inherited to create unique offspring?

What are some ways plants and animals improve their chances to reproduce?

How can lifestyle choices affect your genetics and development?

47. Describe how the hormones progesterone and estrogen work during ovulation and menstruation.

48. True or False – if false change the bold word to make it correct

a) Matching chromosomes are called homologous pairs and are important during mitosis?

b) Haploid means having two sets of chromosomes?

c) Specialized organs to make specialized cells are called zygotes?

d) Meiosis occurs in the testes producing sperm with 23 chromosomes?

e) In both males and females you can have a Y chromosome?

f) Sperm is deposited in the vaginal canal which leads into the ovary?

49. Create a legend and draw a Punnett square showing a cross between a man, heterozygous for long nose,

and a homozygous recessive woman.

50. State the phenotypic and genotypic ratios for the above Punnett square:

51. Give the genotype of the following individuals (use the obvious Dominant and Recessive symbols):

a) A woman who has brown hair but has given birth to a blonde child.

b) A man with a recessive narrow nose.

c) A man who is heterozygous for having freckles.

d) A man who is colour-blind (sex-linked)

e) A woman who is a carrier for hemophilia (sex-linked)


52. Give the phenotype of the following individuals (use the above questions for trait guidance):

a) Nose width genotype is NN.

b) Hair colour genotype (dark or blonde) is Bb.

c) Freckles genotype is ff.

d) Colour-blindness genotype is XCY (state sex, too!)

e) Hemophilia genotype is XhXh (state sex, too!)

53. Explain the following in your own terms, in one short sentence with an example if possible.

Term Description Example

Alleles

Heredity

Recessive

Hybrid

Homozygous

Phenotype

54. What is an “adaptation” and how does it drive the evolution of a species?

55. What is a mutagen?

a) A change in a gene on a chromosome b) A chemical that changes a gene

c) A substance that causes DNA changes d) An organism with altered DNA

56. Which of the following is an example of a natural mutagen?

a) Cigarette smoke b) Cleaning chemicals

c) Industrial waste d) Virus


57. For a mutation to be inherited, it must occur in which of the following types of cells?

a) Cancer cell b) Gamete cell

c) Muscle cell d) Skin cell

58. Which of the following correctly describes cancer cell growth?

a) Cancer cell growth is highly controlled. b) Cancer cells are unspecialized.

c) Cancer cells cannot move to new locations. d) Cancer cells have no nucleus.

59. Match the following terms with the correct description (one description will not be used)

Key Term Definition

cervix A. the process where an egg cell is penetrated by a sperm cell

trait B. a picture of all the chromosomes taken from body cells during mitosis

fertilization C. the opening of the uterus which dilates during child birth do allow delivery

fetus D. a particular disease or disorder with a specific group of symptoms

gametes E. the process that completely separates the two nuclei into two daughter cells

genome F. an embryo at eight weeks of development, with bone cells forming

gene G. the asexual process where a parent cell divides into two equal daughter cells

meiosis H. consists of the full set of genetic material that makes up an organism

cytokinesis I. feature that varies from individual to individual

ovaries J. the cell process and that produces haploid gametes

scrotum K. a fertilized cell that has the combined female and male parent chromosomes

syndrome L. muscular tubes that moves sperm from the testes to the urethra

budding M. structures that carry the sperm cells in a protective case to the ovules

binary fission N. specialized cells necessary for reproduction

chromosome O. protects and nourishes the zygote during development

testes P. the area where sperm are deposited, and through which the baby leaves the body

oviducts Q. produce female gametes by meiosis and release hormones

uterus R. the most common location of fertilization

vagina S. produce male gametes by meiosis and release hormones

vas deferens T. small segments of DNA located at specific places on a chromosome

zygote U. long-stranded DNA chain that carries instructions for cell activities

karyotype V. protects the testes helps maintain a constant lower temperature

W. asexual process where part of a cell pushes outward to form an outgrowth or bud


Nature of Electricity

Essential Outcomes


How does the Atomic Model help to explain static electricity?

What is “Electricity” and how is it created?

What do current, voltage and resistance mean for electrons?

What is a schematic and how are they used as information for a circuit?

60. Friction between two objects produces what?

a) Neutral charge b) More electrons

c) Electric charges d) More protons

61. Two positive charges will?

a) Repel b) Attract

c) Do nothing d) Not enough information to answer

62. A charged object will do what with a neutral object?

a) Repel b) Depends if the charge is positive or negative

c) Attract d) Do nothing

63. Two charged objects are located near one another. Circle the correct term in the brackets to complete

each sentence.

a) Increasing the charge on one of the objects (increases / decreases) the force between the two charged

objects.

b) Increasing the distance between the two objects (increases / decreases) the force between the two

charged objects.

c) Decreasing the distance between the two objects (increases / decreases) the force between the two

charged objects.

64. Draw negative () signs and positive (+) signs in the blank rectangles to represent each charge.

(a) neutral (b) negative (c) positive

65. Explain the difference between an insulator and a conductor:

a) Give an example of an insulator:

b) Give an example of a conductor:


66. Which is not a common energy source used to produce constant electrical energy?

a) Photovoltaic cells b) Friction

c) Piezoelectric crystals d) Thermocouples

67. Which statement correctly defines the difference between static electricity and current

electricity?

a) In static electricity, the charge stays in one place, whereas current electricity is the flow

of charge in a circuit.

b) Static electricity is the flow of charge in a circuit, whereas in current electricity the

charge stays in one place.

c) Static electricity is the flow of negative charge, whereas current electricity is the flow

of positive charge.

d) Static electricity is the flow of positive charge, whereas current electricity is the flow

of negative charge.

68. Which is not an electric load?

a) Battery b) Buzzer

c) Light bulb d) Resistor

69. What is the purpose of an ohmmeter?

a) To measure charge b) To measure current

c) To measure resistance d) To measure voltage

70. When drawing schematics the _____ side terminal is positive

a) Blue b) Long

c) Negative d) Short

71. What is voltage?

a) Speed of electrons b) Energy of electrons

c) Amount of electrons d) Number of electrons

72. Identify the following symbols:

73. Draw a series circuit with a 3V battery, a switch, an ammeter, and a lamp.


74. Draw a schematic diagram for the picture circuit below.

Extension Outcomes

What are the similarities and differences between series and parallel circuits?

How is a household wired to ensure safety?

What is electrical power and how does it vary in appliances?

How can you lower electrical energy use of a household?

75. Which best represents a series pathway?

a) Driving across Canada b) Going through the checkouts at a large grocery store

c) Running laps on an oval track d) Walking home from school

76. Two identical resistors are connected in series to a battery. How does the current through

the second resistor compare to the current through the first resistor?

a) Half the current b) No current

c) The same current d) Twice the current

77. Two identical resistors are connected in parallel to a battery. How does the voltage across

the second resistor compare to the voltage across the first resistor?

a) Half the voltage b) Half the voltage of the battery

c) The same voltage d) Twice the voltage

78. A load is connected to a battery. If a second identical load is added in parallel to the first,

what happens to the total resistance of the circuit and the current leaving the battery?

a) Total resistance decreases and the current decreases.

b) Total resistance decreases and the current increases.

c) Total resistance increases and the current decreases.

d) Total resistance increases and the current increases.


79. Consider the circuit diagram below.

(a) Are the resistors in the above circuit connected in series or parallel? ___________

(b) Determine the voltage at V, current at A for the missing values.

80. Match the term on the left with the proper descriptor. (One descriptor will not be used)

Term Descriptor

_____ 1. coulomb

_____ 2. current

_____ 3. joules

_____ 4. Ohm’s law

_____ 5. power

_____ 6. resistance

_____ 7. series circuit

_____ 8. parallel circuit

_____ 9. static charge

_____ 10. voltage

A. only one path for current to travel

B. charge that remains in one location

C. unit of energy

D. the rate in which energy is transformed

E. amount of energy per unit of charge

F. ability to do work

G. more than one path for current to travel

H. continuous flow of charge

I. relationship of voltage, current, and resistance

J. unit of charge

K. slows down current and changes electrical energy into other forms

81. Which is not a factor of household wiring?

a) It is wired in parallel b) It is wired in series

c) It can be 120 or 240 V d) It uses alternating (AC) current

82. What is the difference between a fuse and a circuit breaker?

83. What is the energy consumption of an 1800 W microwave oven used for 30 min?

a) 0.90 kWh b) 54 kWh

c) 900 kWh d) 54000 kWh


84. A 12000 W resistor is connected to a 60 kV high power line. What is the current, in (A) through this

resistor?

85. Describe two ways of conserving energy in the home.

Exploration Outcomes

What were some early models to explain electricity and how did scientific understanding change?

How is an electroscope used to tell if an object is charged?

86. An electroscope measures?

a) The flow of current b) The presence of charge

c) The amount of resistance d) All of the above

87. If a rubber rod is rubbed with rabbit fur the rod:

a) Stays neutral b) Becomes negatively charged

c) Not enough information to answer d) becomes positively charged

88. When testing an unknown charge, the only certain way to identify the type of charge is to observe its

repulsion with a known charge. Explain why.

89. An electroscope that is charged positive would have its metal leaves separated. A negatively charged rod

is brought close to, but not touching the positive electroscope. What would the metal leaves do?

a) Become negatively charged b) Move closer together

c) Move farther apart d) Not move

90. List a couple differences between charging by conduction and charging by induction?

91. Which best describes a neutral solid object that is charged by conduction?

a) The electrons in the neutral object transfer onto a positively charged object.

b) The electrons in the neutral solid object relocate when a charged object is brought near.

c) The protons in the neutral object transfer onto a negatively charged object.

d) The protons in the neutral solid object relocate when a charged object is brought near.

92. Which best describes a neutral solid object that is charged by induction?

a) The electrons in the neutral object relocate when a charged object is brought near.

b) The electrons in the neutral object transfer onto a positively charged object.

c) The protons in the neutral object relocate when a charged object is brought near.

d) The protons in the neutral object transfer onto a negatively charged object.


Exploring the Universe

Essential Outcomes


Why were the position and motion of visible celestial objects important to past cultures?

How was the process of science important in showing the sun is the centre of our solar system?

How does the position and motion of Earth produce day/night, the phases of the moon, and the seasons?

What objects make up our solar system and Universe?

93. Why did humans begin to analyze the solar system?

94. Who develop the ideas of helio and geocentric and what do the mean?

95. How much time is there between full moons?

a) 1 day b) 1 month

c) 1 weeks d) 1 year

96. What direction do celestial bodies move across the sky?

a) Towards the North b) Towards the East

c) Towards the South d) Towards the West

97. Draw a quick diagram to show the revolution of Earth and its effect on seasons.

98. What do the term spring equinox and summer solstice mean?

99. What does the sun give off?

a) Heat b) Light

c) Energy d) All of the above

100. Explain the difference between fusion and fission reactions. Give an example of each.


101. The nuclear reaction on the sun that produces light uses the element ____________________.

a) Oxygen b) Helium

c) Carbon d) Hydrogen

102. Which of the following shapes is not characteristic of a galaxy?

a) Spiral b) Triangular

c) Elliptical d) Irregular

103. What object is most likely the birthplace of stars?

a) Black holes b) Supernova

c) Nebula d) Neutron star

104. _______________ stars swell near the end of their life cycle into red giants.

a) Yellow b) Red

c) Blue d) White

105. The order of planets in the solar system (from the sun) are as follows:

a) Mercury, Venus, Jupiter, Earth, Mars, Saturn, Uranus, Neptune, Pluto

b) Mercury, Venus, Earth, Mars, Saturn, Jupiter, Neptune, Uranus, Pluto

c) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune Pluto

d) Mercury, Mars, Earth, Venus, Jupiter, Saturn, Uranus, Neptune, Pluto

106. ______________ are large pieces of ice that orbit the sun.

a) Asteroids b) Meteors

c) Comets d) Meteoroids

107. The Milky Way is…

a) The Sun b) A nickname for our solar system

c) A celestial object d) The galaxy containing our Sun and Earth

108. The area between Mars and Jupiter is…

a) Asteroid belt b) Kuiper belt

c) Orion’s belt d) Oort cloud

109. Describe the basic life cycle of a star.


Extension Outcomes

How do astronomers measure the great distances in the universe?

What can an astronomer learn about a star by looking at light?

What is the purpose of the various objects humans put in space?

110. A light year is a measurement of

a) Distance b) Time

c) Speed d) Brightness

111. The colour of a star depends on its

a) Temperature b) Size

c) Distance d) Position

112. What term is used to describe the actual amount of light given off by a star at a standard distance?

a) The spectrum b) The apparent magnitude

c) The absolute magnitude d) The actual magnitude

113. Which of the following instruments can be used to separate white light into its component colours?

a) A photometer b) A CCD camera

c) A spectroscope d) A refractor

114. Which of the following colours of light has the shortest wavelength?

a) Red b) Green

c) Blue d) Violet

115. Choose the most appropriate term for the study of the origin and changes of the universe.

a) Astronomy b) Astrology

c) Cosmology d) Cosmetology

116. What is red-shift and what does it tell us about our universe?

117. Describe some of the robotic objects currently exploring space and their jobs.


D3 – Exploration Outcomes

How can you measure the location of objects in the sky?

How does the tracked location of visible celestial objects change over time?

What are some current goals in Canadian and International space exploration?

What risks/benefits exist with current space projects and what are the possible impacts for humans?

118. Explain how an astrolabe works to measure locations using the terms azimuth and altitude.

119. The main function of a telescope is

a) To gather light b) To magnify objects

c) To form images d) To change the path of light rays


VOCABULARY LISTING FOR ALL UNITS

ATOMS AND ELEMENTS:

ELEMENT ATOM WHMIS HHPS SDS PURE MIXTURE COMPOUND MOLECULE

DIATOMIC HETEROGENEOUS HOMOGENEOUS METALS NON-METALS STATE/PHASE

LUSTRE DUCTILITY MALLEABILIITY SOLUBILITY CONDUCTIVITY METALLOIDS REACTIVITY

COMBUSTIBILITY TOXICITY PHYSICAL PROPERTIES CHEMICAL PROPERTIES PRECIPITATE

COMBUSTION CORROSION OXIDATION LAW OF CONSERVATION OF MATTER

PHYSICAL CHANGE CHEMICAL CHANGE SUBATOMIC ELECTRON NEUTRAL PROTON

NEUTRON ORBIT VALENCE AMU ATOMIC MASS ATOMIC NUMBER BOHR DIAGRAM

PERIOD GROUP FAMILY MENDELEEV PERIODIC LAW TRANSITION METALS

REPRODUCTION

CHROMOSOME GENE DNA TRAIT HEREDITY INTERPHASE MITOSIS CYTOKINESIS

ASEXUAL BINARY FISSION CELL CYCLE GENETIC DIVERSITY GAMETE DIPLOID HAPLOID

HOMOLOGOUS PAIR MEIOSIS HORMONE TESTOSTERONE ESTROGEN PROGESTERONE

(ALL MALE PARTS) (ALL FEMALE PARTS) OVULATION MENSTRUAL CYCLE FERTILIZATION

ZYGOTE EMBRYO FETUS ALLELE DOMINANT RECESSIVE GENOTYPE PHENOTYPE

HETEROZYGOUS HOMOZYGOUS PUNNETT SQUARE ADAPTATION NATURAL SELECTION

MUTATION MUTAGEN CANCER CARCINOGEN

THE NATURE OF ELECTRICITY

NEUTRAL CONSERVATION OF CHARGE INSULATOR CONDUCTOR POLARIZATION ELECTRICITY

GENERATOR CELL COULOMB VOLTAGE VOLT VOLTMETER CURRENT AMPERE/AMP

AMMETER RESISTANCE RESISTOR OHM LOAD BATTERY SWITCH SERIES PARALLEL

SHORT CIRCUIT OVERLOAD CIRCUIT BREAKER FUSE POWER kWh EFFICIENCY EnerGuide

EXPLORING THE UNIVERSE

CONSTELLATION POLARIS RETROGRADE PLANET STAR PTOLEMY COPERNICUS GALILEO

KEPLER GEOCENTRIC HELIOCENTRIC SOLSTICE EQUINOX REVOLUTION ROTATION CORE

FUSION NEBULA SUPERNOVA BLACK HOLE GALAXY MOON TERRESTIAL ASTEROID

METEOROID METEOR METEORITE COMET ASTEROID BELT KUIPER BELT OORT CLOUD

LIGHT-YEAR A.U. ASTRONOMY COSMOLOGY RED SHIFT APPARENT MAGNITUDE

ABSOLUTE MAGNITUDE SPECTROSCOPE TELESCOPE EM SPECTRUM ESCAPE VELOCITY

GEOSYNCHRONOUS SATELLITES GPS PROBES ROVERS ISS

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Atoms and Elements - Weebly€¦ · What are the symbols of the first 20 elements and other common ones? What symbols and systems help people use chemicals safely at home, work and