CLASSIFICATION OF MATTER

VIJITHA V.

PHYSICAL SCIENCE

N.S.S.T.C PANDALAM

REG NO: 13304020

Elements, Compounds and Mixtures

“ single, attached, play play…”

ElementsDefinition of an element:

An element is a pure substance which cannot be split up into two or more

simpler substances by chemical means.

Sugar is not an element as it can be broken down into carbon and water.

Note that an element:

• Consists of only one kind of atom,

• Cannot be broken down into a simpler type of matter by either physical or chemical means

• Can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen).

Elements

Chemical Symbols of Elements

Chemists use symbols to represent elements.

For example, O represents oxygen while Fe represents iron.

Element Symbol Element Symbol

Calcium Ca Mercury Hg

Carbon C Neon Ne

Hydrogen H Silicon Si

Iron Fe Sodium Na

CompoundsNote that a compound:

• can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means),

• has properties that are different from its component elements, and

• always contains the same ratio of its component atoms.

A compound is a substance which is made up of two or more elements chemically combined together.

What is a compound?

- Chemical reactions taking place.

Qn: Is this a compound?

It only contains one type of element.

Qn: Is this a compound?

It only contains one type of element.

H

O

HO

O

Qn: Is this a compound?

It is not chemically combined.

ELEMENTSCOMPOUNDhydrogen

(colourless gas)

oxygen(colourless

gas)

lighted splint

heat, light and

explosion

water(colourless

liquid)

Making compounds from their elementsExample: Making water (picture)

Water molecule

Oxygen molecule

Hydrogen molecule

mixture of

hydrogen and

oxygen

water

Example: Making water (models)

heat, light and

explosion

Summarizing• A compound is made up of two or more

elements chemically joined together• A compound has a fixed composition• Every compound has a unique chemical

formula• A compound has a completely different

properties from its elements• A chemical reaction (decomposition or

electrolysis) is needed to separate the elements in the compound

MixturesDefinition of a mixture:

A mixture is not a pure substance as it contains a mixture of atoms of

molecules which are not chemically combined together.

Mixtures• Note that a mixture: • consists of two or more different elements

and/or compounds NOT chemically combined.• Can be homogeneous or non-homogeneous • can be separated into its components by

physical means, and • often retains many of the properties of its

components.

Mixtures

• Examples of mixtures include muddy water and air.

Air is made up of gases such as nitrogen and oxygen mixed together.

ConclusionAn element is a pure substance which cannot be

split up into two or more simpler substances by chemical means.

A compound consist of a fixed number of different kinds of atoms chemically combined together.

A mixture is not a pure substance as it contains a mixture of atoms of molecules which are not chemically combined together.