C4 - predicting and identifying reactions and products (from PMT)

Question 1

why do elements in the same group have similar chemical properties?

Answer 1

they have a similar electron configuration (same number of outer shell electrons)

Question 2

what group of the periodic table are the alkali metals? why are they called the alkali metals?

Answer 2

-group 1
-they react with water to form alkaline solutions with a very high pH

Question 3

what are the general properties of the alkali metals?

Answer 3

-low melting points
-very reactive
-soft
-low density

Question 4

what gas is produced when an alkali metal reacts with water?

Answer 4

hydrogen

Question 5

what is formed when an alkali metal reacts with oxygen?

Answer 5

metal oxide

Question 6

what is form when alkali metals react with chlorine?

Answer 6

metal chloride (white precipitates)

Question 7

why are alkali metals often stored in oil?

Answer 7

to prevent them reacting with oxygen and water vapour in the air

Question 8

what are the properties of the noble gases?

Answer 8

-low boiling points
-low density
-inert

Question 9

what are the elements in group 7 of the periodic table called?

Answer 9

halogens

Question 10

what is the colour and state of chlorine at room temperature?

Answer 10

pale green gas

Question 11

what is the colour and state of bromine at room temperature?

Answer 11

red-brown liquid

Question 12

what is the colour and state of iodine at room temperature?

Answer 12

black solid

Question 13

why are the halogens at different states at room temperature?

Answer 13

because they have different melting and boiling points
as you go down group 7, melting and boiling points increase

Question 14

what are the properties of halogens?

Answer 14

-increasing melting and boiling points
-diatomic
-reactive

Question 15

describe the trend in reactivity of the halogens. howe does this affect the rate of reaction?

Answer 15

-reactivity decreases down the group
-rate of reaction also decreases down the group

Question 16

what is formed when hydrogen reacts with a halogen?

Answer 16

hydrogen halide

Question 17

chlorine reacts with hydrogen in the presence of sunlight but bromine requires a flame. why?

Answer 17

reactivity decreases down the group so bromine requires more energy for the reaction to occur

Question 18

when does a halogen displacement reaction occur?

Answer 18

when a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide ions.

Question 19

why does reactivity decrease down group 7?

Answer 19

halogens need to gain one electron to obtain a stable electron configuration. as you go down group 7 atomic radius and electron shielding increase. attraction between the nucleus and outer shell electrons decreases so it is harder for the atom to gain an electron meaning reactivity decreases.

Question 20

what colour are solutions of chlorine, bromine and iodine?

Answer 20

chlorine water - colourless
bromine water - orange
iodine solution - brown

Question 21

what are the general properties of transition metals?

Answer 21

-hard
-high density
-high melting and boiling points
-less reactive than alkali metals
-form coloured compounds
-useful as catalysts
form ions with different charges

Question 22

what colour precipitate forms when sodium hydroxide reacts with calcium ions?

Answer 22

white

Question 23

what colour precipitate forms when sodium hydroxide reacts with copper(II) ions?

Answer 23

blue

Question 24

what colour precipitate forms when sodium hydroxide reacts with iron(II) ions?

Answer 24

green

Question 25

what colour precipitate forms when sodium hydroxide reacts with iron(III) ions?

Answer 25

brown

Question 26

what colour precipitate forms when sodium hydroxide reacts with zinc ions?

Answer 26

-white precipitate at first
-re-dissolves with excess NaOH to form a colourless solution

Question 27

describe the test for sulfate ions

Answer 27

-add HCl to remove any CO3^2- ions which would obscure the results
-add a couple of drops of barium chloride
-if sulfate ions are present, a white precipitate of barium sulfate will form

Question 28

describe the test for carbonate ions

Answer 28

-add a few drops of HCl to the sample in a test tube
-connect this test tube to a test tube of limewater
-if carbonate ions are present, carbon dioxide will be produced. limewater will turn cloudy when CO2 is bubbled through

Question 29

describe the test for halide ions

Answer 29

-add a couple of drops of nitric acid to react with the carbonate ions which would obscure the results
-add a couple of drops of silver nitrate
-observe the colour of the precipitate

Question 30

what colour precipitate is formed when silver nitrate is added to a chloride solution?

Answer 30

white precipitate of silver chloride

Question 31

what colour precipitate is formed when silver nitrate is added to a bromide solution?

Answer 31

cream precipitate of silver bromide

Question 32

what colour precipitate is formed when silver nitrate is added to an iodide solution?

Answer 32

yellow precipitate of silver iodide

Question 33

what is the result of the flame test on lithium ions?

Answer 33

crimson flame

Question 34

what is the result of the flame test on sodium ions?

Answer 34

yellow flame