yr 9 - chemistry revision - atomic structure

yr 9 - chemistry revision - atomic structure

Structure of an atom

• Protons and neutrons called nucleons are present inside the nucleus

• Electrons revolve around the nucleus

• Atomic number- number of protons

• Atomic mass/mass number - number of protons and neutrons

Multiple Choice

Atomic number is the number of

• nucleons

• neutrons

• protons

• electrons

Multiple Choice

Atomic mass is the number of

• nucleons

• neutrons

• protons

• electrons

Electronic configuration

• When drawing or writing electronic configuration, you are only allowed

• 2 electrons on the first shell.

• 8 on the 2nd.

• 8 on the third.

• Any leftover are on the 4th.

Multiple Choice

The electronic configuration of Magnesium is

• 2,8,4

• 2,8,6

• 2,8,2

• 2,8,8

Multiple Choice

The electronic configuration of chlorine is

• 2,8,7

• 2,7,8

• 2,8,6

• 2,8,9

Multiple Choice

The electronic configuration of Fluorine is

• 2, 8

• 2,9

• 2,7

• 2,5

Representing the elements and compounds

• A small number just talks about the element it is behind. E.g. O2 = 2 x O

• Small numbers outside the bracket mean multiply everything inside the bracket by that number E.g. (CO3)3 = 3 x C, 9 x O

Multiple Choice

What is the total number of atoms in H₂SO₄

• 3

• 7

• 6

• 5

Multiple Choice

What is the number of atoms in HNO₃

• 3

• 4

• 5

• 6

Multiple Choice

What is the number of atoms in Mg(NO₃)₂

• 3

• 5

• 8

• 9

Relative Atomic Mass (Ar) 

• Carbon has 6 protons and 6 neutrons

• it is given a relative atomic mass of 12 

Relative Atomic Mass (Ar) 

• Oxygen has 8 protons and 8 neutrons

• Carbon has 6 protons and 6 neutrons

Multiple Choice

Relative atomic mass of Cobalt is

• 27

• 59

• 32

Multiple Choice

Relative atomic mass of Arsenic is

• 42

• 33

• 75

Relative formula mass of a compound

• The relative formula mass (Mr) of a compound is the mass of all the elements in the compound added together.

Sodium chloride - relative mass formula

NaCl

Multiple Choice

Relative formula mass of H₂SO₄ is

• 96

• 100

• 98

• 94

Multiple Choice

Relative formula mass of HNO₃ is

• 61

• 62

• 63

• 60

Multiple Choice

Relative formula mass of FeSO₄ is

• 150

• 151

• 152

• 153

Multiple Choice

Relative formula mass of Mg(NO₃)₂ is

• 86

• 134

• 100

• 148

PERCENTAGE COMPOSITION

PERCENTAGE =  Relative atomic mass Ar     X 100

                  Relative formula mass Mr

Multiple Choice

The percentage of sodium in Sodium hydroxide NaOH is

• 58%

• 40%

• 2.5%

• 1%

Multiple Choice

The percentage composition of sulphur in Sulphuric acid H₂SO₄

• 98%

• 2%

• 33%

• 65%

Multiple Choice

The percentage composition of chlorine in Magnesium chloride MgCl₂ is

• 94%

• 74%

• 26%

• 37%