1.1 Atomic structure

Question 1

1.1.1 Atoms , elements, compounds

What is a compound?

Answer 1

• formed from elements by chemical reactions
• formation of one or more new substances
• 2 or more elements chemically combined

Question 2

1.1.2 Mixtures

What is a mixture?

Answer 2

• Consists of two or more elements/compounds which are not chemically combined

Question 3

1.1.2 Mixtures

How can a mixture be separated?

Answer 3

1. Filtration:
   * Separates insoluble substances from soluble substances, in a solvent
2. Crystallisation:
   * separates a soluble substance from a solvent, by evaporation
3. Simple distillation:
   * separates a liquid from a mixture, by evaporation & condensation
4. fractional distillation:
   * separates a mixture, into different parts (fractions). Substances with high BP condense at the bottom
   substances with low BP condense at the top.
5. Chromotagraphy:
   * separates small amounts of dissolved substances by running a solvent alone absorbent paper

Question 4

1.1.2 Development of atom model

Model 1 of the atom:

John Dalton’s model

Answer 4

John Dalton: atoms were tiny spheres that could not be divided.
just a solid sphere

Question 5

1.1.2 Development of atom model

Model 2 of the atom

JJ Thompson

Answer 5

JJ Thompson: discovered electrons
Atoms were spheres of positive charge, with negative charges spread throughout

Plum Pudding model

Question 6

1.1.2 Development of atom model

Model 3 of the atom

Ernst Rutherford

Answer 6

Rutherford, Geiger, Marsden: discovered electrons orbitting around the nucleus
* fired alpha particles at a piece of very thin gold foil, which scattered
* the mass of an atom was concentrated in a nucleus, which was charged

Most particles pass straight through foil, a few deflected.

Question 7

1.1.2 Development of atom model

Model 4 of the atom

Niels Bohr

Answer 7

Niels Bohr: electrons orbit the nucleus at specific distances in certain fixed energy levels/shells

Positive charged nucleus could be subdivided, each particle has the same amount of positive charge. Discovery of proton.

Question 8

1.1.2 Development of atom model

Model 5 of the atom

James Chadwick

Answer 8

James Chadwick: discovery of neutral electric charge in nucleus – Neutron

Question 9

1.1.4 Charges of subatomic particles

What are the charges of the subatomic particles?

Answer 9

Proton: +1
Neutron: 0
Electron: -1

Question 10

1.1.5 Sixe and mass of atoms

Mass of the subatomic particles

Answer 10

Proton mass: 1
Neutron mass: 1
Electron mass: very small

Question 11

1.1.5 Size and mass of atoms

What is the mass number & proton numbers

Answer 11

Mass number: neutron + proton : bigger number
Atomic number: Proton = Electron: smaller number

Question 12

1.1.5 Size and mass of atoms

What is an isotope?

Answer 12

Same element, different number of neutrons

Question 13

1.1.6 Relative atomic mass

What is the relative atomic mass?

Answer 13

it is the average value that takes account of the abundance of the isotopes of the element.

Question 14

1.1.6 Relative atomic mass

Formula

Answer 14

(% of isotope 1 × mass of isotope 1) + (% of isotope 2 × mass of isotope 2) ÷ 100

Question 15

1.1.7 Electronic structure

What is the maximum number of electrons an element can have on each shell?

Answer 15

2,8,8