This presentation by Hooria Shahzad is about elements,compounds and mixtures. About their properties, composition and their differences.

1. ELEMENTS, COMPOUNDS
& MIXTURES
BY: HOORIA SHAHZAD

2. WHAT ARE ELEMENTS ?
ELEMENT :
 is a substance made up of only one kind of atom.
 cannot be broken down into simple substances by
physical or chemical means.
 have same atomic number.
 118 elements are known.
 are represented by symbols.

3. EXAMPLES OF
ELEMENTS
DIAMOND COPPER NEON GAS

4. PERCENTAGES OF NATURALLY
OCCURING ELEMENTS IN
EARTH’S CRUST,OCEANS AND
ATMOSPHERE
CRUST OF
EARTH
OCEANS ATMOSPHER
E
Oxygen 47% Oxygen 86% Oxygen 21%
Silicon 28% Hydrogen 11% Nitrogen 78%
Aluminium 7.8% Chlorine
1.8%
Argon 0.9

5. WHAT ARE COMPOUNDS?
COMPOUND :
 is a substance made up of two or more
elements chemically combined together.
 lose their original properties and produce new
substances.
 can be broken down into simpler type of matter by
chemical means but not by physical means.
 has different properties from its component elements.

6. EXAMPLES OF COMPOUNDS

7. CLASSIFICATION OF COMPOUNDS
Compounds can be classified as ionic or covalent.
Ionic compounds do not exist in independent molecular form.
They form a three dimensional crystal lattice, in which each ion
is surrounded by oppositely charged ions.
These oppositely charged ions attract each other strongly, as a
result ionic compounds have high melting and boiling points.
A molecule is a true representative of the covalent compound
and its formula is called molecular formula.
A molecular formula is a chemical formula that shows the
number and kinds of atom in a molecule.

8. SOME COMMON COMPOUNDS
WITH THEIR FORMULAE
COMPOUND CHEMICAL FORMULA
Silicon dioxide (Sand) SiO2
Sodium hydroxide (Caustic
Soda)
NaOH
Ethane C2H6
Calcium oxide (Quick Lime) CaO
Calcium carbonate (Lime
Stone)
CaCO3
Urea NH2CONH2
Benzene C6H6

9. WHAT ARE MIXTURES ?
MIXTURE :
 is an impure substance made up of two or more elements
physically combined together.
 can be broken down by physical means.
 no chemical changes take place.
 substances held together by physical forces.
 The properties of an elements in a mixture
remain same.
 has no formula.

10. EXAMPLES OF MIXTURES
SALAD
SOIL
SOUP

11. TYPES OF MIXTURES
 THERE ARE TWO MAJOR TYPES OF MIXTURES:
• A Heterogeneous Mixture has differences throughout a
sample.
 EXAMPLES: salt, pepper, cereal, rocks
• A Homogeneous Mixture is the same throughout a sample.
 EXAMPLES: salt water solution, iodine, vinegar
HETEROGENEOUS HOMOGENEOUS
Means “different” Means “the same”

12. MIXTURES VS. COMPOUNDS
COMPOUNDS MIXTURES
DEFINATION It is formed by the chemical
combination of atoms of
the elements.
Mixture is formed by the
simple mixing up of the
substances.
PROPERTIES In compounds the
elements lose their original
properties and form new
substances which are
entirely different from them.
In mixtures the properties
of an element remain
same.
COMPOSITION Compounds always have a
fixed composition by mass.
Mixtures do not have fixed
composition.
JOINED OR NOT The components cannot be
separated by physical
means.
The components can be
separated by physical
methods.
MELTING POINTS Compounds have sharp
and fixed melting points.
Mixtures do not have sharp
and fixed melting points.

13. Thank you for
watching. 