Elements compound and mixtures

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4.1: Elements

Element: An element is a pure substance that can not be further broken down into two or more substances. Through chemical process

Sugar can be broken down into elements so i is not an element nor is water.

Classification of elements

Elements are classified

Metallic or non-metallic

Metalloids

Physical states

(REFER TO TABLE In BOOK PG63)

ATOMS AND MOLECULES

ATOMS: Atoms are part of an element that cannot be further simplified.(Atom has the properties of the element it has been simplified from)

MOLECULES: Molecules are two or more atoms chemically combined together

POLY-ATOMIC MOLECULES: Three or more atoms chemically combined together

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4.2: COMPOUNDS

A compound is a pure substance containing elements that are chemically in a fixed ratio.

here in the image down below it shows a COMPOUND

Water is made up of 2 elements of HYDROGEN and 1 element of OXYGEN.

The ratio of elements in water is always (2:1)

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Composition of a compound:

A compound is made up of Molecules or Ions which are chemically combined together

Ions are electrically charged particles and there charge is either (+) or(-)

Given below is a water molecule

and a Sodium chloride molecule(salt)

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PROPERTIES OF A COMPOUND:

A compound has different properties from the elements that form it.

CHEMICAL FORMULA OF A COMPOUND

Given below shows the chemical formula of a Water molecule

So it shows that there are 2 elements of Hydrogen and a single element of oxygen.

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Bracket compounds solving :

Pb(NO3)2

Here this is the formula for a compound now we have to find the ratio:

The simplest way is to multiply all the numbers in the bracket by the multiple outside.

For .E.g: Pb(NO3)2

the ratio is:

lead:nitrogen:oxygen

1:2:6

DECOMPOSITION OF A COMPOUND

Thermal decomposition

Electrolysis

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4.2: MIXTURES

A mixture is made up of two or more substances that are not chemically combined.

The mixtures' elements are not in a fixed ratio.

Difference b/w Compounds

and Mixtures

Mixture

Compound

SEPERATION

The

elements of a mixture can be separated by physical process such as

Filtration,Distillation

The

elements of a compound can be separated by chemical processes such as

Electrolysis, thermal Decomposition

PROPERTIES

The

chemical properties of a mixture is same as it’s components

The

chemical properties of a compound is different from those of it’s constituent

elements.

ENERGY CHANGE

Non-chemical

reaction takes place when a mixture is forms usually there is little or no

energy

Chemical

reaction takes place when a compound is formed usually there is an energy

change the reactants may get hot or cold.

COMPOSITION

Elements

are found in any kind of compositions

Elements

are present in a fixed ratio.