Periodicity

Question 1

How are elements arranged in the periodic table

Answer 1

Atomic number
-in order of increasing atomic number
Groups
- elements arranged in vertical columns called groups
- each element in a group has atoms with same number of outer shell electrons and similar properties
Periods
- elements are arranged horizontal rows called periods
-number of periods gives the number of the highest energy electron shell in an element’s atom

Question 2

what is periodicity

Answer 2

repeating trends in properties of the elements

Question 3

what are the properties of periodicity

Answer 3

electron configuration
ionisation energy
structure
melting points

Question 4

what happens to atomic radius as you go from left to right across a period

Answer 4

atomic radius decrease because the increased number of protons create more positive charge attraction for electrons which are in the same shell similar shielding

Question 5

what are blocks

Answer 5

are elements that are divided corresponding to their highest energy sub-shell

Question 6

what does ionisation do

Answer 6

measures how easily an atom loses electrons to form positive ions

Question 7

what is first ionisation

Answer 7

energy needed remove an electron from atoms in oone mole of gaseous atoms

Question 8

what are the three factors affecting ionisation

Answer 8

Nuclear charge - more protons in nucleus the greater the attraction
Atomic radius-bigger the atom the further the outer electrons are from nucleus and the weaker attraction to the nucleus
Electron shielding - an electron in the outer-shell is repelled by electrons in complete inner shells weakening the attraction of the nucleus

Question 9

what is successive ionisation energy

Answer 9

patterns in successive ionisation energy for an element gives us important information about the electronic structure of that element

Question 10

Why are successive ionisation energy always larger

Answer 10

The second ionisation energy of an element is always bigger than the first ionisation energy.
This is because the ion formed, is smaller than the atom and the proton to electron ratio in
the 2+ ion is greater than in the 1+ ion. The attraction between nucleus and electron therefore stronger

Question 11

how are ionisation energy linked to electron structure

Answer 11

The fifth electron is in a inner
shell closer to the nucleus and
therefore attracted much more
strongly by the nucleus than the
fourth electron.
It also does not have any
shielding by inner complete shells of electrons

Question 12

Why has Helium the largest first ionisation energy

Answer 12

its first electron shell closest to the nucleus and has no shielding affects from inner shells. It has a bigger first ionisation energy than H as it has one more proton

Question 13

why do first ionisation energy decrease down the group

Answer 13

Atomic radius increases
More inner shells so shielding increases
Nuclear attraction on outer electrons decreases
First ionisation decrease

Question 14

why is there a general increase in first ionisation across a period

Answer 14

Nuclear charge increases
Same she’ll do similar shielding
Nuclear attraction increases
Atomic radius decreases
First ionisation increases

Question 15

Why has N a have a much lower first ionisation energy than Neon

Answer 15

This is because Na will have its outer electrons in a 3s shell further from the nucleus and is more shielded. So Na’s outer electron is easier to remove and has lower ionistion enrgy

Question 16

Why is there a small drop from Mg to Al

Answer 16

Al starting to fill a 3p subshell whereas Mg has its outer electrons in the 3s subshell. The electrons in the 3s subshell are slightly easier to remove because the 3p electrons are higher in energy and are also slightly shielded by the 3s electrons

Question 17

Why is there a small drop from P to S

Answer 17

With sulphur there are 4 electrons in the 3p subshell and the 4th is starting to doubly fill the first 3p orbital.
When the second electron is added to a 3p orbital there is a slight repulsion between the two negatively charged electrons which makes the second electron easier to remove.

Question 18

What is metallic bonding

Answer 18

is the electrostatic forces of attraction between the positive metal ions and the delocalised electron

Question 19

what are the three main factors that affect the strength of metallic bonding

Answer 19

1. Number of protons/ Strength of nuclear attraction.
   The more protons the stronger the bond
2. Number of delocalised electrons per atom (the outer shell electrons are
   delocalised)
   The more delocalised electrons the stronger the bond
3. Size of ion.
   The smaller the ion, the stronger the bond

Question 20

why does Mg have a stronger metallic bond than Na and a higher melting point

Answer 20

The Metallic bonding gets stronger because in Mg
there are more electrons in the outer shell that are released to the
sea of electrons. The Mg ion is also smaller and has one more
proton. There is therefore a stronger electrostatic attraction
between the positive metal ions and the delocalised electrons
and higher energy is needed to break bonds

Question 21

what is the arrangement of diamond

Answer 21

tetrahedral arrangement of carbon atoms four covalent bonds per atom

Question 23

When do we talk about intermolecular force

Answer 23

When simple molecular structures are present

Question 24

Why are silicon carbon oxygen and chlorine classified as p orbitals

Answer 24

They have the highest energy electrons in the p orbital