COMPOUNDS

Compounds and Bonding

What is a compound?

What is a pure substance?

Gold is a pure substance. The surrounding rock is a mixture of different elements and compounds.

Pure substances are composed of one type of particlePure substances have fixed physical and chemical properties

Pure substances are either elements OR compounds

pure substances

MATTER

Can it be physically separated?

Can it be chemically decomposed?

NO

mixtures

NO

element

YES

compound

Concept Map

Review: What are chemical elements?

SodiumBromine

Aluminum

Elements are pure substances composed of only ONE type of atom.

Gold

There are approximately 117 known elements of which only 88 occur naturally. Each element has its own symbol. Elements are organized on the periodic table.

(Au)

A Kaboom Key Concept!An element is a pure substance composed entirely of one type of atom!

A closer look at elements

Elements are substances composed of one type of atom. For example, helium gas (He), is composed of individual helium atoms.

Some elements, like hydrogen gas (H2), are composed of diatomic molecules. Each molecule consists of two hydrogen atoms that are chemically bonded together. What are the other elements that exist as diatomic molecules?

ELEMENTS THAT EXIST AS DIATOMIC MOLECULESELEMENTS THAT EXIST AS DIATOMIC MOLECULES

Individually, these elements only exist as PAIRS of atoms.

When these elements combine in reactions to make compounds, they are no longer elements so they do not need to be in pairs!

Remember:BrINClHOF

or the super 7

What is a compound?

Sodium chloride GlucoseWater

are pure substancescomposed of TWO or more elementsatoms held together by chemical bondscan only be broken apart or formed by a chemical reaction

What happens in a chemical reaction?

reactants are converted to productsbonds are first brokenatoms are rearrangednew bonds form to make different compounds

This unit is all about the types of bonds that hold atoms together to form compoundsionic bonds in compounds like sodium chloride

covalent bonds in compounds like glucose

Assignment

FIND 5 substances in your home that are chemical compounds.