Atomic Structure and the Periodic Table

Question 1

How many elements are there?

Answer 1

about 100 (118)

Question 2

What is a compound?

Answer 2

Two or more elements chemically bonded

Question 3

How would you separate an insoluble solid from a liquid?

Answer 3

Filtration

Question 4

How would you obtain copper sulphate crystals from copper sulphate solution?

Answer 4

Crystalisation

• put the solution in an evaporating basin
• warm the solution by placing the evaporating basin over a boiling water bath
• stop heating when crystals begin to form around the edge of the basin
• After the remaining solution has cooled down, pour the excess liquid away (or filter it). Dry the crystals using a warm oven or by patting them with filter paper.

Question 5

How would you separate a solvent from a solution?

Answer 5

Simple distillation

Question 6

How would you separate different liquids from a mixture of liquids?

Answer 6

Fractional distillation

Question 7

How would you separate mixtures of soluble substances?

Answer 7

Chromatography

Question 8

Give an example of when filtration should be used

Answer 8

To seperate water from sand

Question 9

Give an example of when simple distillation shoiuld be used

Answer 9

To separate water from salt

Question 10

Give an example of when fractional distillation is used

Answer 10

To separate different fractions from crude oil

Question 11

Give an example of when chromatography should be used

Answer 11

To separate different dyes

Question 12

What is the plum pudding model of the atom?

Answer 12

The plum pudding model was a model of the atom which suggested that the atom is a ball of positive charge with negative electrons embedded in it.

Question 13

Which experiment disproved the plum pudding model and led to the nuclear model?

Answer 13

Alpha particle scattering led to the conclusion that the mass of an atom was concentrated at the centre, (nucleus) and that this nucleus was charged. This model is called the nuclear model.

Question 14

How did Niels Bohr add to the nuclear model of the atom?

Answer 14

By suggesting and proving that electrons orbit the nucleus at specific distances

Question 15

Who proved the evidence of neutrons, and how long was it after the nuclear model was invented?

Answer 15

James Chadwick, 20 years later

Question 16

What is the atomic number of an atomic?

Answer 16

The number of protons

Question 17

What is the relative mass of a proton?

Answer 17

1

Question 18

What is the relative mass of a neutron?

Answer 18

1

Question 19

What is the relative mass of an electron?

Answer 19

Very small

Question 20

What is the mass number of an atom?

Answer 20

The sum of the protons and neutrons

Question 21

What is an isotope?

Answer 21

An atom of the same element with a different number of neutrons

Question 22

What is the radius of an atom?

Answer 22

0.1nm (1 x 10^-10 m)

Question 23

What is the relative atomic mass of an atom?

Answer 23

An average value that takes into account the abundance of isotopes of the element

Question 24

How are elements in the periodic table arranged?

Answer 24

In order of atomic number (number of protons) and so that elements with similar properties are in columns (groups)

Question 25

What is the same about all elements in the same group of the periodic table?

Answer 25

They have the same number of electrons in their outer shells, and as a results have similar properties

Question 26

How did Newlands order the elements before the discovery of protons, neutrons and electrons, what was the problem with this, and how did Mendeleev overcome them?

Answer 26

By order of atomic weight

The problem with this was that elements were placed in inappropriate groups

He overcame the problems by leaving gaps for undiscovered elements and sometimes changing the order

Question 27

What is a metal?

Answer 27

A metal is an element which reacts to form positive ions

Question 28

What are the group 0 elements called, what are their properties, and what are their trends in terms of reactivity and boiling point?

Answer 28

Noble gases
They are unreactive because they have 8 electrons in their outer shell (helium has only 2)
Their boiling points increase as you go down, and the reactivity doesn’t change, as they are unreactive.

Question 29

What are the group 1 elements called, what are their properties, and what are their trends in terms of reactivity and boiling point?

Answer 29

Alkali metals
They are very reactive, as they have only 1 electron in their outer shells
Their reactivity increases as you go down, as the electrons are further away from the nucleus, and thus the attraction is weaker, making the electron easier to lose

Question 30

What are the group 7 elements called, what are their properties, and what are their trends in terms of reactivity and boiling point?

Answer 30

Halogens
They are diatomic, and all have 7 electrons in their outer shells
As you descend the group, boiling point, and melting points increase. Their reactivities decrease, as the attraction is weaker, meaning its harder to gain an electron

Question 31

Can halogens displace each other?

Answer 31

Yes, a more reactive halogen can replace a less reactive halogen from an aqeuous solution of its salt

Question 32

Remember to revise the properties of transition metals

Answer 32

Dewit