Unit 3. Mixtures and Pure Substances

Pure substances

UNIT 3. MIXTURES AND PURE

SUBSTANCES

Mixtures

VOCABULARY

Complete as follows…

Matter=

Physical=

Chemical=

Means=

Joined=

Procedure=

Retains=

Distilled=

Pure Substances

A portion of matter that has definite chemical and physical

properties.

carbon dioxide (CO2), water (H2O),

nitrogen dioxide (NO2)…

One kind of pure substance:

Elements Pure substance formed by one type of atom that cannot be

separated into simpler substance by physical or chemical means

• Ex. Physical means: distillation, filtration…

• Ex. Chemical means: chemical reaction: substitution, reduction…

Its symbol in the periodic table is its chemical formula

Other kind of pure substance:

Compounds

Pure substance composed of two or more different

elements joined by chemical bonds.

Has a chemical formula with at least two different letter.

Can only be separated by chemical procedures, not physically.

Mixtures

A combination of two or more pure substances that are not

chemically combined.

Each substance retains its properties in the mixture and has

his own chemical formula.

They can be separated physically.

There are two types: homogeneous and heterogeneous, depending

on the capacity of distinguish the different components or

not.

Can you identify the following?

You are going to see a series of photos. Say if each photo

represents an element, compound, or mixture.

Review:

An element is a pure substance which contains just one

type of atom.

A compound is a pure substance which contains two or

more different atoms joined together.

A mixture contains two or more different substances that

are only physically joined together, not chemically.

Element, Compound, or Mixture?

Rocks

Element, Compound, or Mixture?

Rocks

Element, Compound, or Mixture?

Copper

Element, Compound, or Mixture?

Copper

Element, Compound, or Mixture?

Jelly Beans

Element, Compound, or Mixture?

Jelly Beans

Element, Compound, or Mixture?

Table Sugar

Element, Compound, or Mixture?

Table Sugar

Element, Compound, or Mixture?

Diamond

Element, Compound, or Mixture?

Diamond

Element, Compound, or Mixture?

Tea

Element, Compound, or Mixture?

Tea

Element, Compound, or Mixture?

Salt

Element, Compound, or Mixture?

Salt

Element, Compound, or Mixture?

Neon Gas

Element, Compound, or Mixture?

Neon Gas

Element, Compound, or Mixture?

Salad

Element, Compound, or Mixture?

Salad

Element, Compound, or Mixture?

Distilled Water

Element, Compound, or Mixture?

Distilled Water

Element, Compound, or Mixture?

Aluminum

Element, Compound, or Mixture?

Aluminum

Element, Compound, or Mixture?

Lemonade

Element, Compound, or Mixture?

Lemonade

Element, Compound, or Mixture?

Silver

Element, Compound, or Mixture?

Silver

Element, Compound, or Mixture?

Sand

Element, Compound, or Mixture?

Sand

exercises 1)Complete the statements in your notebook:

a) A mixture is a group of two or more …………….

b) All pure substances have a constant chemical ………..

c) A mixture can be separated by ……………. means

d) A pure substance like a compound can be separated by

………… means

e) An element is a pure substance composed by one type of

……….

f) A heterogeneous mixture can be identified using your ……….

g) A homogeneous mixture needs a ………………… to

distinguish all the components