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Chapter 3: Elements combine to form compounds

Pages 70-92By Lester Green Smallwood Academy Gambo

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3.1 CompoundsPages 72-75

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1.22 Identify and write chemical formula of common compounds.

See international rules outlined in textbook on pages 81-83

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1.22.1 Define compound

Pure substances that consist of two or more elements combined in fixed proportions.

Sodium Chlorine

BariumOxygen

LithiumFluorine

PotassiumBromine

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1.22.1 continued…

Water

Two hydrogen atom

One oxygen atoms

H2O

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1.22.1 continued...Hydrogen Peroxide

Two oxygen atoms

Two hydrogen atoms

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1.22.1 continued...Carbon Dioxide

One carbon atom

Two oxygen atoms

CO2

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1.22.1 continued...

Carbon Monoxide

One carbon atom

One oxygen atom

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1.22.1 Define compoundA pure substance made up of more than one

kind of element joined togetherRepresented by a combination of symbolsSymbols known as formulaExamples:

1. H2O

2. MgF2

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1.22.2 Identify whether a compound is ionic or molecular 1. Ionic

Atom gains or loses electrons to form ions

Atom transfer electron(s)

1.22.2 continued…Atom gaining electron becomes negativeAtom losing electron becomes positiveFormed between metals and nonmetals.

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1.22.2 continued…2. Covalent formed between

nonmetals only. Occurs when atoms

shares electrons to form molecules.

This type of bonding may also be called molecular.

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1.22.2 Identify whether a simplecompound is ionic or molecular (covalent)

Ionic compounds formed between metals and nonmetals

Covalent (molecular) compounds are formed between nonmetals only

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1.22.2 continued… ionic or covalent

Ionic

Ionic

Ionic

Covalent

Covalent

Covalent

Sodium Chloride

Magnesium Sulphide

Carbon TetrafluorideSilicon Disulphide

Lithium Nitride

Carbon Dioxide

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Rules for Naming Ionic Compounds (82)

1. Name the metal ion

2. Name the non-metal ion by ending the element name with the suffix “ide” (table 3.1 page 81)

3. Write name of formula

Examples: NaCl

KBr

Sodium Chloride

Potassium Bromide

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Rules for Naming Covalent Compounds (p83)1. Name the first atom

2. Name the second atom by ending the element name with the suffix “ide”

3. Add prefix to the atom names to indicate the number of each atom in the compound

4. Write the name of the compound

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Examples of covalent compounds

CO Carbon Monoxide

CO2Carbon Dioxide

Silicon Tetrachloride SiCl4

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1.22.4 Compound is represented byelement symbols known as a chemical formula

Compounds represented by a combination of element symbols

Symbols known as a chemical formula

Formula indicates the proportion in which elements are present

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1.22.4 continued…Examples

Worksheet: Complete worksheet on name and ratio of elements in a compound

2 atom of Hydrogen and 1 atoms of oxygenH2O

NaCl 1 atom of sodium and 1 atom of chlorine