Unit 1 : Chemical changes and Structure

Question 1

How is elements arranged in the periodic table

Answer 1

Elements are arranged in the periodic table in order of increasing atomic number.

Question 2

What is Vertical columns in Periodic table called and say all the features.

Answer 2

Vertical column in the periodic table is called groups.
Elements in the same group have the same number of outer electrons.
Elements with the same number of outer electrons have similar chemical properties.

Question 3

What is Horizontal rows called in the periodic table and list all the features.

Answer 3

Horizontal rows on the periodic table are called periods. Rows of elements are arranged with increasing atomic number.

increasing atomic number leads to an increasing number of electrons in the outer shell going across a period from left to right.

As the number of outer electrons in the shell increases, the element move from metallic characteristics to non-metal characteristics

Question 4

What bonding are these elements

Li, Be, Na, Mg, Al, K, Ca

Answer 4

Metallic Lattice Bonding

Question 5

What bonding are these elements
B
Si
C (Diamond, Graphite)

Answer 5

Covalent Network

Question 6

What bonding are these Elements

H, N, O, F, Cl, P, S, C60 (Fullerene)

Answer 6

Covalent Molecular

Question 7

What bonding are these elements.

He, Ne, Ar

Answer 7

Monatomic

Question 8

Define Covalent radius and the Units for Covalent Radius

Answer 8

Covalent radius gives us a measure of the size of an atom. It is defined as half the distance between the centres (nuclei) of 2 bonded atoms. The covalent radius is measured in picometres.

Question 9

Describe and explain how the size of an atom changes going down a group

Answer 9

Down a group the atomic size (covalent radius) increases as an extra electron shell is added.

Question 10

Describe and explain how the size of an atom changes going across a period from left to right

Answer 10

Across a period the atomic size (covalent radius) decreases as the nuclear charge increases and attracts the outer electrons closer to the nucleus.

Question 11

What is the first ionisation energy

Answer 11

The first ionisation energy is the energy required to remove one mole of electrons from one mole of atoms in the gaseous state.

Question 12

What is second ionisation energy

Answer 12

The second ionisation energy is the energy required to remove a second mole of electrons from a mole of free atoms .

Question 13

What happens to ionisation energy when going down a group

Answer 13

Going down a group the ionisation energy decreases. This is because the outer electrons are further away from the nucleus.

The screening effect of the inner electron shells reduce the nuclear attraction of the outer electrons, despite the increase of positive nuclear charge

Question 14

What happens to ionisation energy when going across a period

Answer 14

Going across a period ionisation energy increases.
This is because the nuclear charge increases (greater positive charge on the nucleus) and holds the outer electrons more strongly. More energy needs to be supplied to remove the electron

Question 15

State electronegativity

Answer 15

Electronegativity is the attraction an atom involved in a bond has for the electrons of the bond

Question 16

What happens to electronegativity when going down a group

Answer 16

Going down the group, the nuclear charge increases but the number of electron shells also increases. As a result of shielding and an increased distance the outer shell is from the nucleus, electronegativity decreases.

Question 17

What happens to electronegativity when going across a period

Answer 17

The electronegativity increases when going across a period. When going across the period the nuclear charge increases. This pulls the electron shells closer to the nucleus.