C1

Question 1

What is Crystallisation

Answer 1

This technique separates a soluble
substance from a solvent by
evaporation

Question 2

What is simple distillation

Answer 2

This technique separates a liquid from
a mixture by evaporation follow by
condensation

Question 3

What is fractional distillation

Answer 3

This technique separates a mixture into
a number of different parts, called fractions.
Substances with high boiling points condense at
the bottom and substances with low boiling
points condense at the top.

Fractional distillation works because the
different substances in the mixture have
different boiling points.

Question 4

Chromatography

Answer 4

This technique separates small
amounts of dissolved substances
by running a solvent along
absorbent paper

Question 5

John Dalton - Early 1800s

Answer 5

Before the discovery of electrons, John Dalton’s experiments led to the idea that atoms were tiny spheres that could not be divided.

Question 6

JJ Thomson - Late 1800s

Answer 6

The electron was discovered by JJ Thomson. Scientists believed that atoms were spheres of positive charge with negative charges spread throughout - the ‘plum-pudding’ model.

Question 7

Ernst Rutherford - 1908 - 1913

Answer 7

Ernst Rutherford designed an experiment carried out by Geiger and Marsden.
They fired alpha particles at a piece of very thin gold foil (only a few atoms thick) which scattered, leading to the conclusion that the mass of an atom was concentrated in a nucleus, which was charged. It proposed that electrons orbited around the nucleus.

Question 8

Niels Bohr - 1914

Answer 8

Niels Bohr noticed that the light given out when atoms were heated only had specific amounts of energy and he adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances in certain fixed energy levels (or shells). The energy must be given out when excited electrons fall from a high to low energy level.

Later experiments led to the idea that the positive charge of the nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles.

Question 9

James Chadwick - 1932

Answer 9

James Chadwick bombarded beryllium atoms with alpha particles. An unknown radiation was produced. Chadwick
interpreted this radiation as being composed of particles with a neutral electrical charge and the approximate mass of a proton.
This particle became known as the neutron.

Question 10

How to work out PEN

Answer 10

Protons = Electrons
Protons = Atomic Number
Neutrons = Mass Num - Atomic Num

Question 11

What is an Isotope

Answer 11

Atoms of the same element can have different numbers of neutrons

Question 12

HOTPT - John Dalton - 1908

Answer 12

John Dalton published a table of elements that were arranged in order of their atomic weights, which had been measured in various chemical reactions

Question 13

HOTPT - John Newlands - 1864

Answer 13

John Newlands published the law of octaves. However the table was incomplete and elements were placed in
inappropriate groups

Question 14

HOTPT - Dmitri Mendeleev - 1869

Answer 14

Dmitri Mendeleev overcame Dalton’s problem by leaving gaps for the elements that he thought had not been discovered and in some places changed the order based on atomic weight (e.g. Argon and Potassium). Elements with properties predicted by Mendeleev were eventually discovered.

Question 15

Group 0

Answer 15

Elements in Group 0 of the periodic table are called the noble gases. They are nonreactive because their atoms have stable arrangements of electrons. The atoms have eight electrons in their outermost shell, apart from helium, which has just two, but still has a complete outer shell.

The boiling points of the noble gases get higher going down the group. For example helium boils at -269 °C and radon boils at -62°C.

Question 16

Group 1

Answer 16

The alkali metals are very reactive. They need to be stored under oil to prevent them reacting with oxygen and water vapour in the air. The alkali metals have low densities. The metals are very soft and can be cut with a knife. They also have low melting and boiling points.

The properties are due to all the atoms having just one electron in their outermost shell. They only need to lose one electron to get the stable electronic structure of a noble gas.

Question 17

Group 7

Answer 17

The halogens are a group of toxic non-metals that
have coloured vapours. They have low melting and
boiling points, which increase down the group. They
are poor conductors of heat and electricity.