Group 2- textbook ntes

Question 1

why is group 2 called the alkaline earth metals

Answer 1

• their oxides and hydroxides are alkaline

Question 2

as you go down the group the size of the atom

Answer 2

increase as shielding increases down the group

Question 3

melting point

Answer 3

• the electrons in the sea of delocalised electrons are further away from the positive nuclei
• as a result the strength of the metallic bonds decreases going down the group
• therefore melting points of grp 2 decrease slightly going down the group

Question 4

how does Mg react with cold water and steam

Answer 4

• very slow with cold water to form metal hydroxide (aq) and hydrogen
• rapidly with steam to form an alkaline oxide and hydrogen

Question 5

describe solubility of 
Mg
Ca
St
Ba

Answer 5

almost insoluble
soluble
more soluble
dissolves to produce a strongly alkaline solution

Question 6

solubility of sulphates

Answer 6

decreases down the group

Ba- is insoluble

Question 7

what can the insolubility of barium be of use to

Answer 7

simple test for sulphate ions in solution

• solution first acidified with nitric or hydrochloric acid
• barium chloride solution then added
• if a sulphate is present a white precipitate of barium sulphate forms

Question 8

how do group 7 non-metals exist

Answer 8

diatomic molecules

Question 9

what colour is F at room temp

Answer 9

pale yellow gas

Question 10

what colour is Cl at room temp

Answer 10

green gas

Question 11

what colour is Br at room temp

Answer 11

red-brown liquid

Question 12

what colour is I at room temp

Answer 12

black solid

Question 13

down the group grp 7 (physical properties)

Answer 13

darker and denser down the group

Question 14

what is electronegativity

Answer 14

ability of an atom to attract electrons, or electron density towards itself within a covalent bond

Question 15

what does electronegativity depend on

Answer 15

• attraction between the nucleus and bonding electrons in the outer shell

Question 16

electronegativity down the group

Answer 16

decreases going down the group

Question 17

explain why electronegativity decreases going down the group

Answer 17

the shared electrons in the bond get further away from the nucleus as the atoms get larger going down the group
- this makes the shared electrons further from the halogen nucleus and increases the shielding by more inner shells of electrons

Question 18

melting and boiling points in grp 7

Answer 18

increase going down the group

Question 19

explain why melting and boiling points increase going down the group

Answer 19

• larger atoms have more electrons
• this makes the London forces between the molecules stronger
• this means more energy is required to break the intermolecular forces between them