Chemical equations

Question 1

why are elements put into groups

Answer 1

to group together elements that have similar properties

Question 2

how to represent hydrogen in a symbol equation

Answer 2

H
2

Question 3

what is the name given to elements in group 2

Answer 3

alkali earth metals

Question 4

the total mass of reactants=

Answer 4

the total mass of products

Question 5

name the 4 state symbols

Answer 5

s- solids
l- liquids
g- gases
aq- aqeuous

Question 6

Balance the equations on sheet of paper!!!

Question 7

what is fractional distillation

Answer 7

an effective way of seperating miscible liquids, using a fractionating column
-seperation is possible bc of different boiling points of liquids in the mixture

Question 8

mixtures are

Answer 8

easily seperated

Question 9

name 3methods mixtures can be seperated

Answer 9

-filtration
-chromatography
-evaporation

Question 10

state the method of how to seperate a substance in a mixture through chromatography

Answer 10

-draw a line near the bottom of a sheet of filter paper (using a pencil, as the marks insoluble and won’t dissolve the solvent)
-add a spot of ink to the line and place the sheet in a beaker of solvent (water)
-make sure the ink isn’t touching the solvent, so it doesn’t dissolve into it
-place a lid on top of container to stop solvent evaporating
-solvent seeps up the paper, carrying ink with it

Question 11

state the results that will occur for paper chromatography

Answer 11

-if the dyes insoluble, it will stay on the baseline
-if the dyes reached the top of the paper, take the paper out the beaker and leave it to dry

Question 12

when would you need to use fractional distillation rather than simple distillation

Answer 12

FD is used when the mixture contains multiple liquids with similar boiling points

Question 13

describe the technique for filtration

Answer 13

-place a piece of filter paper in a funnel and put the funnel over a beaker
-pour mixture through the funnel
-any insoluble liquids will be caught by the filter paper and its called residue
-any liquid or dissolved substances will pass straight through and is called the filtrate

Question 14

state 2ways to seperate soluble solids from solutions

Answer 14

-evaporation
-crystallisation

Question 15

explain evaporation

Answer 15

-pour solution into evaporating dish

-slowly heat the solution (bunsen burner)and the solvent will then be more concentrated. then crystals start to form

-keep heating the evaporating dish until the crystals are dry

Question 16

explain crystallisation

Answer 16

-pour solution into a evaporating dish and gently heat the solution

-once the solvents evaporated or when crystals form (point of crystallisation) remove dish from heat and leave solution to cool

-salt starts to form crystals as it becomes insoluble in the cold solution

-filter crystals out of solution and leave them in a warm place to dry

Question 17

why is simple distillation used

Answer 17

-to separate out solutions

Question 18

describe the process of simple distillation

Answer 18

-solutions placed in a flask and heated to the liquid evaporates into vapour
-vapours then passed into a condenser where it then condenses back into a liquid
-liquids then collected in a beaker

Question 19

describe the process of fractional distillation

Answer 19

-used to SEPERATE A MIXTURE OF LIQUIDS

-put a mixture in a flask and stick a fractioning column on top and then heat it

-

Question 20

state the certain amount of number of electrons that are allowed in each shell

Answer 20

1st shell- 2
2nd shell- 8
3rd shell-8

Question 21

whats the name given to elements in group 0

Answer 21

noble gases

Question 22

whats meant by an atoms outer shell

Answer 22

shell of electrons furthest from the nucleus

Question 23

state why halogens become less reactive as you move down group 7 of the periodic table

Answer 23

-as you go down the group atomic radius and SHIELDING INCREASE

-means theres a weaker electrostatic attraction between the nucleus and the electron its trying to gain

-means more energys required for a reaction to occur

Question 24

name given to elements in group 1 is

Answer 24

alkali metals

Question 25

what are the properties of group 1metals

Answer 25

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

Question 26

lithium +water—–
sodium +water—–
potassium +water—–

Answer 26

lithium +water—– lithium hydroxide +hydrogen
sodium +water—– sodium hydroxide + hydrogen
potassium +water—– potassium hydroxide + hydrogen

Question 27

what are the physical properties of most non metals

Answer 27

-brittle
-dull
-low melting/boiling points
-lower density
-poor conductors of electricity