atomic structure and the periodic table

Question 1

what is an element

Answer 1

a substance containing only one type of atom

Question 2

what is a compound

Answer 2

when two or more elements are chemically combined in a fixed propotion

Question 3

what is a mixture

Answer 3

when elements or compounds are not chemically combined

Question 4

what is used to separate a mixture

Answer 4

a physical separation technique

Question 5

what is filtration used for

Answer 5

it is used to separate an insoluble solid from a liquid

Question 6

what do we call the liquid that passes through the filter paper

Answer 6

it is called a filtrate

Question 7

what do we call the leftover solid in the filter paper

Answer 7

the residue

Question 8

what is crystallization used for

Answer 8

to separate a soluble solid from a liquid

Question 9

what is simple distillation used for

Answer 9

it is used to separate a soluble substance from a liquid if we want to keep the liquid

Question 10

what is fractional distilation

Answer 10

it allows us to separate two mixed liquids

Question 11

what does a fractionating column do

Answer 11

it ensures that the vapors of the higher boiling point chemical condense back into a liquid into the flask

Question 12

how does fractional distillation work

Answer 12

first both vapors of both liquids are going up the fractionating column although there is more of the lower boiling point liquid. Then as the lower boiling point is reached it becomes pure vapors of liquid A. This leaves liquid B to be collected when its boiling point is reached

Question 13

what is a solvent

Answer 13

a solvent is a liquid that will dissolve substances

Question 14

what is the stationary phase in chromatography

Answer 14

the paper

Question 15

what is the mobile phase

Answer 15

the solvent

Question 16

why does paper chromatography work

Answer 16

it is because each chemical will be attracted to the paper to different extents. strongly attracted chemicals wont move far and weakly attracted chemicals will move further

Question 17

what is the plum pudding model

Answer 17

it is when a ball of positive charge has electrons scattered througout it

Question 18

why did scientists use gold for the alpha particle scattering experiment

Answer 18

it is because gold can be hammered into thin sheets

Question 19

why did they use alpha particles

Answer 19

it is because they have a positive charge

Question 20

what is the nuclear model

Answer 20

the nuclear model has a positive nucleus with a ring of electron and is mostly empty space. Finally it changes to the current model

Question 21

what is the relative mass of an electron

Answer 21

very small or insignificant

Question 22

what is an isotope

Answer 22

isotopes are atoms of an element that have different numbers of neutrons but the same amounts of protons and electrons

Question 23

what are ions

Answer 23

they are atoms that have either gained or lost electrons so have an overall charge

Question 24

what was Johann Döbereiner’s theory

Answer 24

He believed elements with similar properties existed in three and he called these triads. the mains ones he noticed were lithium sodium and potassium. Also he found chlorine, bromine and iodine

Question 25

what was John Newlands theory

Answer 25

he believed that every 8th elements ordered in atomic weight would have similar properties

Question 26

why was Mendeleev table correct

Answer 26

It is because he predicted where the element would be and predicted their properties

Question 27

what are the properties of noble gasses

Answer 27

they are very unreactive
they

Question 28

what happens to the boiling point as you go down group 0

Answer 28

it increases

Question 29

what two categories can you class the metals into and where are they found on the periodic table

Answer 29

highly reactive metals are group one and two
transition metals are found between group 2 and three