It’s Elementary WatsonNOTES

Year 7 ScienceMr Isgro

• Lab coat• Safety glasses (Goggles)• Gloves• Fire extinguisher• Fire blanket• Eye wash• Emergency shower

1. Laboratory Safety Equipment

1. Lab Safety Symbols

2. Materials from Different Cultures

3. Mass and Volume

• The mass of an object is the amount of matter it contains

• Volume is the amount of space it takes up.

https://www.youtube.com/watch?v=kWpgynOgkVE

4. Properties of Materials

• Electrical Conductivity (some metals are better conductors than others)

• Luster (shiny in appearance)• Malleability (able to be shaped upon hitting –

e.g. plasticine). Some metals are more malleable than others (e.g. lead and iron)

• Ductile (able to be drawn out – e.g. copper wire)

5. Element

• An element is made up of one type of atom (He, C, Ar).

• Elements have no charge (number of positive protons are cancelled out by negative electrons).

• Some elements exist as molecules (H2, O2, N2)

6a. Periodic Table

• The purpose of the periodic table is to summarise and predict the properties of elements.

• Elements are arranged by rows (periods) and in columns (groups).

6c. Periodic Table: Metals and Non-metals

6b. Elements to Learn: First 18

• H• He• Li• Be• B• C• N• O

• F• Ne• Na• Mg• Al• Si• P• S

• Cl• Ar

6b. Other Elements to Learn

• Iron - Fe• Copper – Cu• Zinc – Zn• Gold – Au• Mercury – Hg• Lead – Pb• Uranium – U• Platinum – Pt• Titanium - Ti

Element: CarbonEach element in the Periodic Table is denoted by four identifying characteristics: the name of the element, a one or two-letter symbol, the atomic number (above the symbol) and the average mass (below the symbol.

7. Atoms: Subatomic particles

• Atoms are the simplest particle of matter• The are a nucleus (protons and neutrons)

surrounded by electrons

7. Atoms

7. Atom Model: Lithium

P+ = +3e- = -3N = 4 (neutral)Overall charge = 0

7. Atom: Beryllium (Be)P+ = +4e- = -4Overall charge = 0

P = 4N = 5 (neutral)Mass = 9

7. Atom: CarbonP+ = +6e- = -6Overall charge = 0

P = 6N = 6 (neutral)Mass = 12

8. What is the difference between a compound and a molecule?

• A molecule is formed when two or more atoms join together chemically.

• A compound is a molecule that contains at least two different elements.

• Note: All compounds are molecules but not all molecules are compounds.

8. Molecules made of only one type of atom

• Molecular hydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element.

Oxygen molecule O2

Hydrogen molecule H2

Nitrogen molecule N2

9. Compounds are made from more than one type of element

• Examples: Water (H2O), carbon dioxide (CO2) and methane (CH4)

Water H2OCarbon dioxide (CO2)

Methane Molecule CH4

9. Molecules and compounds

• The confusing thing is that the smallest bit of any chemical substances is referred to as a molecule (even compounds).

• A single molecule of molecular hydrogen is made from two atoms of hydrogen (H2)

• A single molecule of the compound water is made from two atoms of hydrogen and one atom of oxygen (H2O).

14. Mixture• A combination/blend of different substances

NOT chemically joined together.

14. Mixture

9. What is a mixture?

• A mixture is a substance made by combining two or more different materials in such a way that no chemical reaction occurs.

• A mixture can usually be separated back into its original components.

• Some examples of mixtures are a tossed salad, salt water and a mixed bag of lollies.

10. Household chemicals

• NaCl (sodium chloride) – table salt for cookingATOMS: 1 sodium +1 chlorine

• HCl (hydrochloric acid) – cleaning bricks and is also stomach acid

ATOMS: 1 hydrogen + 1 chlorine

10. Household chemicals

• NaCO3 (Sodium bicarbonate) – baking soda for baking bread or cakes

ATOMS: 1 sodium + 1 carbon + 3 oxygen

• C6H12O6 (glucose) – simple sugar that is a source of energy made by plants during photosynthesis

ATOMS: 6 carbon + 12 hydrogen + 6 oxygen

10. How many atoms?

• What kind of atoms form this molecule? • How many of each type of atom are there?

Carbon = 5Hydrogen = 8

10. How many atoms?

• What kind of atoms form this molecule? • How many of each type of atom are there?

11. Boiling water: practical

11. Boiling water: practical

Temperature of water over time

Tem

pera

ture

( o C

)

Time (minutes)

12. Chemical change: practical

Observe chemical change by performing chemical reactions: • Mg (magnesium) and HCl (hydrochloric acid)

Observations: flammable gas produced

• Pb(NO3)2 (Lead nitrate) and KI (potassium iodide)

Observations: precipitate (solid) formed

12. Evidence of chemical change

• Temperature change (hot or cold)• Precipitate forms (solid that sinks)• Suspension forms (solid that does not sink)• Gas produced (bubbles or smell)• Light given off (fire/plasma)• Sound (fizz or bang)• Change in mass (heavier or lighter)• Permanent colour change

13. How to Write a Practical Report

• Aim• Apparatus• Method• Risk Assessment (risk to one’s health)• Diagram (always use a pencil and ruler)• Results (often presented in a table)• Conclusion (answer the aim)

13. How to Write a Practical Report

• Title: Hydrogen Gas Preparation

• Aim: To find out what happens when magnesium is added to hydrochloric acid.

• Materials: 5mL hydrochloric acid (HCl), magnesium ribbon (Mg), 2 test tubes, matches, wooden splint

13. How to Write a Practical Report

• Method: 1. Add 5 cm piece of magnesium ribbon to 5 ml

HCl in one test tube. 2. Place the second test tube was placed mouth

downward over the top of the first test tube to collect the gas produced by the reaction.

3. After a few minutes, place a lit wooden splint inside the second test tube

4. Observe and record your results.

13. How to Write a Practical Report• Risk Assessment:

Risk Precaution

Acid can burn your skin and eyes

Wear lab coat and safety glasses.

Glass can cut when broken

Handle carefully and clean up breakages

Flame is hot Handle lit splint carefully and remove flammable objects

13. How to Write a Practical Report

• Observations: - When the magnesium was added to the HCl, bubbles

formed. - Condensation appeared on the inside of the second

tube. - The lit wooden splint inside the second test tube

caused a "popping” sound.

• Conclusions: Since a burning splint will cause hydrogen to pop, it was concluded that the gas formed was hydrogen.

13. Drawing and labeling scientific diagrams

15. Homogenous and Heterogeneous

15. Homogenous and Heterogeneous

Homogeneous mixture – Uniform composition• All of the substances are evenly distributed

throughout the mixture (salt water, air, blood).

15. Homogenous and Heterogeneous

• Heterogeneous mixture – Not uniform composition

• the substances are not evenly distributed (chocolate chip cookies, pizza, rocks)

16. Solutions

• A solution is a homogeneous mixture made up of a solute dissolved in a solvent.

Example: Coca Cola• Solute (dissolved)– CO2, Sugar, etc…• Solvent (dissolved in)– Water

17. Water

• Water is a solvent in everyday life, the environment, and industry.

Aqueous solutions: Solutions in which water is the solvent.• For example, when sugar is dissolved in water,

the solution obtained is called an aqueous solution of sugar. Soft drink is an aqueous solution.

18. Suspension

• A suspension is a heterogeneous mixture in which one substance does not dissolve in another.

• This gives a cloudy (opaque) mixture that settles over time.