18

Grade 9 Science

Unit 1

Atoms, Elements, & Compounds

Name:

Section #:

Chapter 3 (Elements Combine to form Compounds) - Terms

Name: ______________________

chemical bonds

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chemical change

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chemical formula

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chemical name

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combustion

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condensation

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corrosion

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covalent compound

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dissolving

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evaporation

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freezing

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ionic compound

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melting

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molecule

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physical change

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products

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reactants

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Chapter 3:Elements combine to form compounds.

Compounds

· A substance made of two or more kinds of combined in fixed proportions.

· Represented by a .

· Chemical hold them together.

· Can be either or .

( Methane Gas…CH4)

(Sodium Chloride… NaCl)

Characteristics

Examples

Covalent Compounds

· Atoms combine by sharing electrons to form _______________.

· A molecule is a group of ________ held together by sharing one or more pairs of electrons.

· Formed by _______________ only.

· They do NOT conduct ________________.

· May be a _________, __________ or __________ at room temperature.

Ionic Compounds

· Atoms gain or lose electrons to form ____________.

· All the +ve ions attract all the

-ve ions everywhere in the same crystal.

· Formed from __________ & ____________.

· All are __________ at room temperature.

· High __________ & __________ points.

· Will conduct electricity when dissolved in __________.

· Also called __________.

Naming Compounds

· Every compound has a…

1.

2.

· Rules for Naming Compounds

· Ionic Compounds

· See pg. 81-2

· Covalent Compounds

· See pg. 83

Physical and Chemical Changes

Physical Changes

Chemical Changes

Properties

· The ____________________ of a substance may have changes BUT the __________ holding the atom together in molecules and ions have not been broken and no new _________ have been made.

· Tend to be __________ to reverse.

· Produce __________ substances with new _____________; may or may not be noticeable.

· New __________ are formed while others are __________.

· *Chemical equations can be written for _______ chemical changes.

· **There are 5 pieces of evidence of a chemical change.

Examples

* Chemical Equations, for example the composition of water.

In a chemical reaction, the mass of the reactants = the mass of the products. The elements are conserved BUT not the compounds.

**The 5 pieces of evidence of a Chemical Change are:

1.

2.

3.

4.

5.

Applications of Chemical Changes…

1.

2.

3.

Complete Core Lab Activity 3-3C pg. 92-3

Complete STSE “Plastics and Modern Life”

Chapter 3 - Elements Combine to form Compounds

Name: ________________________________

1.What is a chemical bond? (72)

__________________________________________________________________________________________________________________________________________________________________________

2.What are two kinds of compounds? (73-74)

__________________________________________________________________________________________________________________________________________________________________________

3.Describe two ways that elements can combine to form compounds. (73-74)

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

4.How are atoms connected to each other in covalent compounds? (73-74)

__________________________________________________________________________________________________________________________________________________________________________

5.What needs to happen to atoms of different elements to allow them to combine to form an ionic compound? (74)

__________________________________________________________________________________________________________________________________________________________________________

6.In a water molecule, how many atoms are connected to each? (75)

(a)oxygen atom? __________

(b)hydrogen atom?__________

7.Calcium bromide, CaBr2, is an ionic compound. (75)

(a)In a crystal of calcium bromide, how many bromine atoms are there for every atom of calcium? __________

(b)Do you expect that calcium bromide would be a solid, liquid or gas at room temperature? Explain.

__________________________________________________________________________________________________________________________________________________________________________

8.A compound is formed from a metal and a non-metal. Is this compound ionic or covalent? How

do you know? (74)

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9.A compound is a solid at room temperature and conducts electricity when dissolved in water. Is the compound ionic or covalent? (75) ____________________________

10.A compound is a gas at room temperature. Is the compound ionic or covalent? (75) _____________________________

11.A compound is a solid at room temperature. Devise a test that you could use to determine whether the compound is ionic or covalent. (75)

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

12.(a)How many parts are there in the name of an ionic compound? (82) __________

(b)What does each part describe? (82)

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13.(a)How many parts are there in the name of an covalent compound? (83) __________

(b)How are prefixes used in naming covalent compounds? (83)

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14.How can you tell if a compound is ionic or covalent by looking at the chemical formula? (81)

__________________________________________________________________________________________________________________________________________________________________________

15.Complete the following table. (81)

Name of Ion

Symbol

nitride

O2-

fluoride

P3-

sulfide

chloride

Mg2+

16.Name the following compounds. (82-83)

(a)LiBr_____________________________________________

(b)NaI_____________________________________________

(c)K2S_____________________________________________

(d)MgF2_____________________________________________

(e)Al2O3_____________________________________________

(f)Ca3N2_____________________________________________

(g)N2S4_____________________________________________

(h)BF3_____________________________________________

(i)NO2_____________________________________________

(j)PBr5_____________________________________________

(k)SiF4_____________________________________________

17.Identify the following as either ionic or covalent. (81)

(a)sodium chloride_____________________________________________

(b)magnesium sulfide_____________________________________________

(c)carbon tetrachloride_____________________________________________

(d)silicon disulfide_____________________________________________

(e)lithium nitride_____________________________________________

18.(a)Name two kinds of change that can affect matter.(86-87)

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(b)What kind of change involves the formation or breaking of bonds between atoms. (88)

_____________________________________________________________________________________

(c)Which kind of change involves only changes to the appearance of a substance. (88)

_____________________________________________________________________________________

19.Identify the following as a chemical or physical change. (88-90)

(a)melting_____________________________

(b)combustion_____________________________

(c)evaporation_____________________________

(d)freezing_____________________________

(e)corrosion_____________________________

(f)dissolving_____________________________

(g)fruit ripening_____________________________

20.Define the terms reactant and product. (88)

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

21.List five pieces of evidence that indicate a chemical change. (89)

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

22.In a propane gas fireplace, the propane gas combines chemically with oxygen gas. The new substances made in this reaction are carbon dioxide and water. Identify the reactants and products in the reaction. (88)

Reactants: ___________________________________________________________________________

Products: ____________________________________________________________________________

23.How can you distinguish between a chemical change and a physical one. (88-89)

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

24.Explain why liquid water changing into steam is a physical and not a chemical change. (88-89)

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Write the names of the following ionic compounds:

AlI3 _____________________________________________________

Na2O_____________________________________________________

Mg3P2_____________________________________________________

AgI_____________________________________________________

CaSe_____________________________________________________

K2S_____________________________________________________

RbF_____________________________________________________

Ag3N_____________________________________________________

KBr_____________________________________________________

Sr3P2_____________________________________________________

CdS_____________________________________________________

Ag2O_____________________________________________________

Cs2S_____________________________________________________

CaI2_____________________________________________________

NaF_____________________________________________________

Write the names of the following Covalent compounds:

SO3_____________________________________________________

CCl4_____________________________________________________

N2O3_____________________________________________________

P2O5_____________________________________________________

C4H10_____________________________________________________

SiO2_____________________________________________________

Goal•Complete a concept map to demonstrate your knowledge of how atoms form bonds.

What to Do

Use the following words to complete the concept map. You can use each term more than once.

attract, covalent bond, ionic bond, ions, metal atom, non-metal atom, opposite charges, share electrons, transfer electrons

Goal•Practise reading chemical formulas for ionic and covalent compounds.

Rules for writing the names of ionic compounds containing two elements

1. Write the name of the metal ion.

2. Write the name of the non-metal ion by ending the element name with the suffix "ide".

1. Write the names of the following compounds.

(a)NaCl

(b)KI

(c)LiF

(d)CuO

(e)PbCl 2

(f)ZnBr2

(g)Al2O3

Rules for writing the names of covalent compounds

1. Write the name of the first atom.

2. Write the name of the second atom by ending with the suffix "ide".

3. Add prefixes to the atom names to indicate the number of each atom in the compound (mono, di, tri, tetra).

2. Write the names of the following compounds.

(a)CO2

(b)SO2

(c)H2O

(d)CCl4

(e)NH3

Goal•Demonstrate your knowledge of forming ionic compounds.

What to Do

Show your knowledge of ionic bonding by answering the following questions in the spaces provided.

Questions

1.Examine the Bohr-Rutherford diagrams below. Circle the atoms that are stable.

Hint: remember the maximum number of electrons each energy level can hold.

(a)

(b)

(c)

(d)

(e)

2.The following Bohr-Rutherford diagram represents an oxygen atom. Examine the diagram, then answer the following questions.

(a)Why is this not a stable electron arrangement?

_________________________________________________________________

(b)What would make this atom stable?

_________________________________________________________________

(c)Use a coloured pencil to adjust the diagram so that it shows a stable electron arrangement.

3.Define the term “ionic bond.”

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[Goal•Check your understanding of Chapter 3.

Note: A periodic table and an ion chart are required for this review.

What to Do

Circle the letter of the best answer.

 1.Which of the following can form a covalent compound?

A.a metal and a metal

B.a metal and a non-metal

C.a non-metal and a non-metal

D.two metals and a non-metal

 2.What happens when ionic compounds are formed?

A.atoms always gain one or more electrons

B.atoms always lose one or more protons

C.atoms gain or lose one or more electrons

D.atoms gain or lose one or more protons

 3.Ionic compounds are in what state at room temperature?

A.any of the three states

B.gas

C.liquid

D.solid

 4.When naming an ionic compound, which element should you name first?

A.the element with the lowest atomic number

B.the metal

C.the metal with the name that comes first alphabetically

D.the non-metal

 5.When naming a covalent compound with two atoms of the same element, what suffix is used?

A.di

B.ide

C.mono

D.tri

 6.What is the name of MgS?

A.magnesium sulphate

B.manganese sulphate

C.magnesium sulphide

D.manganese sulphite

 7.Which of the following is a physical change?

A.fire

B.sugar dissolving in water

C.rotting fruit

D.rusting

 8.Which is an example of a physical change used traditionally in Newfoundland and Labrador?

A.burning lamp oil made from blubber

B.drying fish

C.smoking fish

D.tanning hides

Match the Term on the left with the best Descriptor on the right.Each Descriptor may be used only once.

Term

Descriptor

_____ 9.atom

_____10.ionic compound

_____11.product

_____12.reactant

A.refers to metal and a non-metal chemically bonded

B.the substance produced in a chemical reaction

C.non-metal that has a negative charge

D.ion made of several atoms joined together by covalent bonds

F.the smallest particle of an element that has the properties of the element

G.material that is made during a chemical reaction

H.the starting material in a chemical reaction