Periodic Table (GRP 1, 17, 18)

Question 1

7 Physical Properties of Alkali Metals

Answer 1

1. Shiny, grey solids
2. Soft
3. Low density
4. Low MP/BP
   5.Good conductors of heat & electricity
5. Malleable
6. Ductile

Question 2

2 Chemical Properties of Alkali Metals

Answer 2

1. Very reactive with oxygen and water in the air
2. React with water to produce metal hydroxide + hydrogen gas

Question 3

Trends down the group (Alkali Metals)

Answer 3

1.MP/BP decreases
2. Density increases
3. Reactivity increases

Question 4

Why does MP/BP decrease down the grp? (Alkali Metals)

Answer 4

As no. of e shells increase, strength of electrostatic forces of attraction decrease, making it easier to overcome electrostatic forces of attraction. So, MP/BP decrease

Question 5

Why does density increase down the grp? (Alkali Metals and Halogens)

Answer 5

As no. of e shells increase, atomic radii increase, so volume increases. However, atomic mass increases more than vol, so density increases down the grp. (Density=Mass/Volume)

Question 6

Why does reactivity increase down the grp? (Alkali Metals)

Answer 6

As the no. of e shells increase, strength of electrostatic forces of attraction decrease, making it easier to lose valence e. So, metal is more reactive down the grp.

Question 7

What do Halogens exist as?

Answer 7

Diatomic molecules
(meaning 2 atoms chemically combined by covalent bond to form molecule)

Question 8

What do halogens form after gaining an electron

Answer 8

Halide

Question 9

2 Physical Properties of Halogens

Answer 9

1.Relatively low MP/BP
2.Poor conductors of heat and electricity

Question 10

Chemical Properties of Halogens

Answer 10

1.Reacts vigorously with metals to form ionic salts
(e.g. sodium+chloride= sodium chloride)
2. Reacts with non-metals to form covalent compounds
3. Displacement Reaction

Question 11

What happens in a displacement reaction

Answer 11

More reactive halogen displaces less reactive halogen to form aqueous solution of its ion

Question 12

Trends down the grp (Halogens)

Answer 12

1.MP/BP increase
2.At room temp, halogens exist as gas to solid states down the grp
3.Density increases
4. Colour darkens
5. Reactivity decreases

Question 13

Why does MP/BP increase down the grp? (Halogens)

Answer 13

As no. of e shells increase, molecular size of halogens increase, so increase in extensiveness of intermolecular forces of attraction between molecules. So, more energy required to overcome forces of attraction, so MP/BP increase.

Question 14

Why does reactivity decrease down the grp? (Halogens)

Answer 14

As no. of e shells increase, strength of electrostatic forces of attraction between -ve charged and +ve charged ions decrease. So, theres less tendency to gain an e, making it less reactive down the grp.

Question 15

What do noble gases exist in atmosphere as?

Answer 15

1.Monoatomic (Consists of only 1 atom)

Question 16

Why are noble gases the least reactive/ unreactive elements in the periodic table?

Answer 16

They have a fully filled e shell, so they are stable, and do not need to lose, gain or share electrons

Question 17

Properties of Noble Gases

Answer 17

1. Low MP/BP
2. Insoluble in water
3. Colourless gases at room temp
4. Odourless
5. Inert/Unreactive

Question 18

What are groups on the periodic table, and what are the characteristics of elements down the same group?

Answer 18

The vertical columns. Elements in the same group have similar physical and chemical properties, the atomic radius increases down the grp, and have same no. of valence electrons.

Question 19

What are periods down on the periodic table, and what are the characteristics of elements on the same period?

Answer 19

The horizontal rows. Elements of the same period have the same no. of shells and increasing atomic number.