C4

Question 1

Which number tells you which element an atom is?

Answer 1

The proton (atomic) number

Question 2

What happen to early attempts to find connection between the chemical properties of elements and their relative atomic masses?

Answer 2

They were dimissed by scientific community

Question 3

Briefly outline the contribution that Doberiner made to the early development of the periodic table

Answer 3

In 1817 Johann Dobereiner proposed his ‘ law of triads’. He realised the relative atomic mass of the mass middle element in group in a group of three elements ( that had similar properties) was close to the average of the other two elements

Question 4

Outline the contributions that Newlands made to the early development of the periodic table

Answer 4

He arranged the known elements in order of their atomic masses. He proposed a’law of octaves’ meaning every eighth element had similar properties.This did not work for all the known elements , so was dissmied by the scientific community.

Question 5

State the contributions that Mendeleev made to the development of the periodic table.

Answer 5

He put the known elements in order of relative atomic mass but left gaps for undiscovered elements. He also predicted what the properties of these undiscovered elements might be.

Question 6

Why was Mendeleev’s table ultimately more successful than had come before?

Answer 6

He put the known elements in order of relative atomic mass but left gaps for undiscovered elements. He also predicted what the properties of these undiscovered elements might be.

Question 7

In terms of sub-atomic particles what do the relative atomic mass and the atomic number tell us?

Answer 7

The atomic number gives us the number of protons and electrons in an atom of an elements. The relative atomic mass tell us the number of protons +the number of neutrons

Question 8

Where is a group in the periodic table?

Answer 8

A vertical column of elements

Question 9

Where is a period in the periodic table?

Answer 9

A horizontal row of elements

Question 10

Approximately where can metals and non metals be found on the periodic table?

Answer 10

Metals on the left and in the middle, non-metals on the right

Question 11

What are the group 1 elements also known as?

Answer 11

The alkali metals.

Question 12

Describe the appearance of the group 1 metals when they have been freshly cut.

Answer 12

They are silver and shiny.

Question 13

What happens to the group 1 metals when they are exposed to air? Why is this?

Answer 13

They tarnish and become dull due to reacting with moisture and oxygen in the air

Question 14

Describe the reactions of lithium, sodium and potassium in cold water.

Answer 14

All the alkali metals react vigorously with cold water. In each reaction, hydrogen gas is given off and meal hydroxide is produced.

Question 15

What is the reaction of lithium and water?

Answer 15

Lithium + water =lithium hydroxide + hydrogen

Question 16

What is the symbol equation for sodium reacting with water?

Answer 16

2Na(s) + 2H2O (I) = 2NaOH(aq) + H2 (g)

Question 17

Alkali metals react vigorously with chlorine. Describe the appearance and formula of the product formed.

Answer 17

A colourless, crystalline salt is formed with the formula MCl ie LiCl or KCl

Question 18

Give an example of show that the alkali metals become more reactive as the group it descended.

Answer 18

In their reactions with water, the reactions become increasingly vigorous as you go down the group.

Question 19

State and explain one precaution necessary when working with group 1 metals and alkalis.

Answer 19

Strong alkalis are corrosive , so care must be taken when they are in use for example by using goggles and gloves

Question 20

Identify the states and appearances of chlorine , bromine, and iodine at room temperature and pressure.

Answer 20

Chlorine = green gas
Bromine = reddish-brown liquid
Iodine = Dark-purple

Question 21

Halogens consist of diatomic molecules: what does this mean?

Answer 21

It means the element exist as molecules of twos

Question 22

Describe the reactivity of the halogens as the group descends. Give an example to show this.

Answer 22

The reactivity of the halogens decreases as we move down the group. This can be shown by looking at displacement reactions. For example, When chlorine is added to sodium bromide solution , the chlorine takes the place of the bromide, Because chlorine is more reactive than bromine. This make it sodium chloride.

Question 23

How can the trend in reactivity for halogens be demonstrated by displacement reactors?

Answer 23

The most reactive halogen displaces all the other halogens from the solution of their salts, and is itself displaced by none of the others. The least reactive halogen displaces non of the others and is itself displaced by all the others

Question 24

State and explain the safety precautions necessary when working with halogens

Answer 24

Because the halogens are very reactive and poisonous, car must be taken when using them. Chlorine is only used in a fume cupboard. Iodine should not be handled ( it will damage skin) Gloves may be used and goggles should be worn

Question 25

Describe the general structure of an atom.

Answer 25

Protons and neutrons in a very small central nucleus with electrons arranged in shells around the nucleus.

Question 26

Recall the relative masses and charge of protons, neutrons and electrons.

Answer 26

Protons; mass = 1 ; charge = 1 +
Neutron; mass = 1 ; charge = 0
Electron; mass = negligible; charge = 1-

Question 27

In an atom what are there equal numbers of ?

Answer 27

Electrons and protons

Question 28

All atoms of the same element have the same number of what?

Answer 28

Protons

Question 29

Elements in the periodic table are arranged in order of what?

Answer 29

Proton number

Question 30

What happens to some elements Eg lithium and potassium, when heated ?

Answer 30

They emit distinctive flame colours

Question 31

Why did the study of line spectra help chemists to discover new elements?

Answer 31

Because each element has individual, characteristics line spectrum.

Question 32

How did the development of new practical techniques such spectroscopy aid the development of science?

Answer 32

It helped scientists discover new elements

Question 33

Describe how you can use the periodic table to work out the number of protons , electrons and neutrons in an atom.

Answer 33

Proton number is the same as the atomic number
Electron number is the same as the atomic number
Neutron number is the mass number minus the atomic number

Question 34

In terms of electrons and shells, what happens across a period?

Answer 34

The same shell fills up with electrons a period

Question 35

In terms of electrons and shells, what happens down a group?

Answer 35

The element in the same group have the same number of electrons in their outer shell ( this is the same as the group number) but they all have different umber of shells

Question 36

What determines the chemical properties of an elements ?

Answer 36

Its electron arrangement

Question 37

What is the fact that molten compound of metals with non-metals conduct electricity evidence for?

Answer 37

It shows that they are made up of charged particles (called ions)

Question 38

What is an ion?

Answer 38

An atom that has gained or lost an electrons and has an overall charge

Question 39

Identify and explain the charge on the ions of group 1 elements?

Answer 39

Group 1 atoms form 1+ ions because they lose one electron in order to have a full outer shell of electrons

Question 40

Identify and explain the charge on the ions of group 7 elements?

Answer 40

Group 7 elements form 1- ions because they gain one electron in order to have a full outer sell of electrons

Question 41

what is the type of bonding in the compounds formed from group 1 and group 7 elements?

Answer 41

Ionic bonding

Question 42

Solid ionic compounds form crystals, why?

Answer 42

Because the ions are arranged in a regular lattice .

Question 43

What happens to the ions when ionic crystals melt or dissolves in water?

Answer 43

The regular crystal lattice breaks down into positive and negative ions that are free to move.

Question 44

Why can ionic compounds conduct electricity when molten or dissolved in water?

Answer 44

Because the ions are charged and they are able to move around independently in the liquid