Unit 1 Periodicity

Question 1

How are elements in the periodic table arrangement, what does this predict?

Answer 1

In order of increasing atomic number
Allows chemists to make accurate predictions of physical properties and chemical behaviour of any element based on its position

Question 2

What is the layout in periodic table?

Answer 2

Groups - vertical columns contain elements w similar chemical properties common number of outer electrons
Periods - row of elements arranged in increasing atomic number increasing number of outer electrons
Move from metallic to non

Question 3

What are the types of bonding and examples of elements in each?

Answer 3

Metallic
Li,Be,Na,Mg,Al,K,Ca
Covalent Molecular
H2,N2,O2,F2,Cl2,P4,S8,C60
Covelent network
B,C(diamond,graphite),Si
Monotomic
Noble gasses

Question 4

What are the 3 main trends in the periodic table?

Answer 4

Covalent radius-measure of the size of an atom
Electronegativity-measure of attraction an atom involved in a bond has for the electrons of the bond
Ionisation energy-the energy required to remove one mole of electrons from one mole of gasues atoms

Question 5

What happens to covalent radius across a period?

Answer 5

Decreases across a period due to an increase nuclear charge the electrons are pulled more closely to the nucleus resulting in decrease in radius

Question 6

What happens to covalent radius down a group?

Answer 6

Increases-due to an increase in the number of electron shells and shielding
As number of shells increases shielding occurs blocking outer electrons from nucleus resulting them to be less strongly attracted to nucleus and increase in radius

Question 7

What happens to electronegativity across a period?

Answer 7

Increases-due to increase nuclear charge which allows the nucleus to pull the electrons more strongly resulting in increase in electronegativity

Question 8

What happens to electronegativity down a group?

Answer 8

Decreases-die to increase in the number of electron shells and shielding
As number of electrons increase more shells become full and shilling occurs resulting in decreased electronegativity

Question 9

What happens to ionisation energy across a period?

Answer 9

Increase-due to increase nuclear charge as the electrons are pulled more closely to nucleus,more energy is required to remove them relating in increased ionisation energy

Question 10

What happens to ionisation energy down a group?

Answer 10

Decreases-due to increases in number of electron shells and shielding
As the number of electrons increases more shells become full and shielding occurs. The outer electrons are held less tightly to the nucleus and require less energy to remove lowering ionisation energy

Question 11

How do u write equations for ionisation energies?

Answer 11

First
E(g)->E+(g) + e-

Second
E+(g)->E2+(g) + e-

Question 12

Why is there a large jump from ionisation energy 2nd and 3rd?

Answer 12

The third ionisation energy shows a massive increase because it requires electron to be removed from a full energy shell

Question 13

Describe bonding and structure in metallic elements?

Answer 13

Metallic bonding occurs between the atoms of metal elements. The outer electrons are delocalised(free to move)
This produces an electrostatic force of attraction between positive metal ions and negative delocalised electrons

Question 14

Describe structure and bonding in colvent molecular?

Answer 14

Covalent molecules are small groups of atoms held together by strong covalent bonds inside the molecule and weak intermolecular forces between the molecule

Question 15

Describe bonding and structure in colelent network?

Answer 15

Covelent network are large, rigid three-dimensional arrangements of atoms held together by strong covalent bonds

Question 16

Describe structure and bonding in monoatomic elements?

Answer 16

Single, unattached particles. They are stable atoms. Weak London dispersions forces

Question 17

Compare density,mp, conductivity of monotomic, covelent, network and metalllic?

Answer 17

Monotamic(noble gasses)-low density,low mp,non conducter
Covelent-low density,low mp,non conducter
Network-very high density,very high mp,non conductor(exept graphite)
Metallic-high density,high mp,conducter