C1 - Atomic structure & The Periodic Table

Question 1

What is an Element?

Answer 1

A substance where all of the atoms are the same (made of one type of atom)

Question 2

What is a compound?

Answer 2

A substance made up of two or more different elements chemically combined in fixed proportions.

Question 3

What is a mixture?

Answer 3

2 or more elements or compounds that are not chemically combined.

Question 4

What is a molecule?

Answer 4

Any elements chemically combined even if they’re the same element

Question 5

What are the 2 stages of simple distillation

Answer 5

1. Evaporate the liquid by heating.
2. Condense the vapour back to a liquid by cooling.

Question 6

In Chromatography, what is the stationary phase (1), and the mobile phase (2)?

Answer 6

1. Paper - It does not move.
2. Solvent - moves up the paper.

Question 7

What does a pure compound (1) and a compound in a mixture (2) look like when chromatography has taken place?

Answer 7

1) Singular spot in all solvents.
2) Separate into different spots depending on the solvent.

Question 8

Why do we draw the starting line in pencil when carrying out chromatography?

Answer 8

If we drew the line in pen, the pen ink could dissolve in the solvent and move up the paper.

Question 9

Filtration:

Answer 9

Used to separate an insoluble solid from a liquid.

Mixture poured through filter paper.

Question 10

Crystallisation:

Answer 10

Used to separate a soluble solid from a liquid.

If left for a few days, liquid evaporates & leaves behind the soluble solid.

Gently heating the solution speeds up the process.

Question 11

Fractional distillation is used to…

Answer 11

Separate a mixture of different liquids.

Question 12

Describe how the results of the alpha scattering experiment lead to the nuclear model

Answer 12

Alpha particles (with positive charge) fired at gold foil.

Pass straight through - Atoms are mainly empty space.

Deflected - Centre of atom (nucleus) has positive charge.

Bounce back - Centre of atom (nucleus) contains a great deal of mass.

Question 13

Modification of nuclear model: Discovery of electron energy levels

Answer 13

Bohr proposed that electrons orbit the nucleus at specific distances

Question 14

Modification of nuclear model: The proton

Answer 14

Positive charge in nucleus is due to tiny positive particles called protons

Question 15

Modification of nuclear model: The neutron

Answer 15

Chadwick discovered the nucleus also contains neutral particles called neutrons

Question 16

Radius of an atom:

Answer 16

0.1 nanometres

1 x 10^-10 m

Question 17

Radius of the nucleus:

Answer 17

1 x 10^-14 m

Question 18

Relative charges of Proton, Neutron & Electron

Answer 18

Proton: +1
Neutron: 0
Electron: -1

Question 19

Relative mass of Proton, Neutron & Electron

Answer 19

Proton: 1
Neutron: 1
Electron: Very Small

Question 20

Define Atomic number & Mass number

Answer 20

Atomic number - Number of protons & electrons

Mass number - Number of protons & Neutrons

Mass number - Atomic number = Number of Neutrons

Question 21

Atoms of the same element have:

Answer 21

Same number of protons.

However number of neutrons is not fixed.

Question 22

Define Isotopes

Answer 22

Atoms of the same element with different numbers of neutrons

Question 23

Define Ions

Answer 23

Atoms which have an overall charge.

(They have lost or gained electrons)

Question 24

Describe Relative atomic mass

Answer 24

An average that takes account of the abundance of the isotopes of the element.

Question 25

Relative atomic mass equation:

Answer 25

(Mass no. of isotope 1 x percent abundance of isotope 1) + (mass no. of isotope 2 x percent abundance of isotope 2) ________________________________________ 100

Question 26

Describe early attempts to arrange the elements into a periodic table

Answer 26

Arranging elements in order of their atomic weights. Newlands “Law of octaves”: In order of increasing atomic weight. Every 8th element reacts in a similar way.

Question 27

Explain why Mendeleev’s periodic table successfully predicted the properties of elements

Answer 27

• Arranged elements in order of increasing atomic weight. • If needed, he switched the order of specific elements to for the patterns of other elements in the same group. • Realised that some elements had not been discovered - left gaps where he thought an element was missing. • Predicted the properties of undiscovered elements based on other elements in the same groups.

Question 28

How are elements arranged in a modern periodic table

Answer 28

• Arranged in order of atomic number • Group 0: noble gases

Question 29

Why are group 0 elements unreactive?

Answer 29

They have a full outer shell, so they are stable. This means they won’t react.

Question 30

How do the boiling points of group 0 elements vary down the group?

Answer 30

The boiling point increases as you go down the group.

Question 31

Where are metals & non-metals positioned on the periodic table?

Answer 31

• Metals are found to the left and towards the bottom • Non-metals are found towards the right and top

Question 32

Describe how metals react to form positive ions

Answer 32

• They lose electrons to achieve a full outer shell • This gives them the stable electronic structure of a group 0 noble gas. *Metals always form positive ions

Question 33

Group 1 metals reaction with oxygen

Answer 33

2 metal atoms transfer their outer electrons to oxygen. 2 metal ions are formed & an oxide ion is formed. A metal oxide is formed

Question 34

Group 1 metals reaction with chlorine

Answer 34

Metal atom & chlorine atom react. Metal ion & chlorine ion is made. A metal chloride is formed.

Question 35

Group 1 metals reaction with water

Answer 35

• The metal reacts rapidly & there is effervescence - tells us that a gas is being produced. • Alkaline solution is made.

Question 36

Explain why group 1 metals reaction more rapidly as we move down the group

Answer 36

• Outer electrons are more easily lost. • This is because there is a greater distance between positive nucleus & negative outer electron. • As this distance increases, the outer electron is less attracted to the positive nucleus • Outer electron is repelled by electrons in the internal energy levels (shielding) - decreases the attraction between the nucleus and outer electron • Shielding increases as we move down group 1 as elements have more electrons in internal energy levels.

Question 37

Describe how group 7 elements consist of molecules with 2 atoms

Answer 37

2 atoms of a group 7 element react and share a pair of electrons to form a covalent bond. Group 7 molecule is produced.

Question 38

Describe how melting and boiling points of group 7 elements change down the group

Answer 38

The melting & boiling points increase as we move down group 7

Question 39

Describe how group 7 elements form covalent compounds when they react with non-metals

Answer 39

Both elements require 1 extra electron so they form a covalent bond. A covalent compound is formed.

Question 40

Describe how group 7 elements form Ionic compounds when they react with metals

Answer 40

When a halogen atom reacts with a metal atom, the halogen gains 1 electron. The extra electron gives the halogen an overall charge of -1 (Chloride ion)

Question 41

Describe & explain how the reactivity of halogens changes down group 7

Answer 41

•The halogens get less reactive as we move down group 7. • Electrons are gained less easily as the distance between the nucleus & outer electron increases. • Greater shielding of outer electron.

Question 42

A (…) halogen can displace a (…) halogen from an aqueous solution of its salt

Answer 42

1) (more reactive) 2) (less reactive)

Question 43

Describe the properties of transition elements

Answer 43

• Hard & strong metals. • High melting points. • High density • Much less reactive than group 1 metals • Can form ions with different charges • Form coloured compounds • Useful as catalysts