chemistry 1

Question 1

what is the radius of a nucleus

Answer 1

1 x 10^-14m

Question 2

what are the relative masses of the subatomic particles

Answer 2

proton = 1
neutron = 1
electron = very small

Question 3

what is an isotope

Answer 3

atoms of the same element which have the same number of protons but a different number of neutrons

Question 4

what do you mention in a question asking to describe the isotope

Answer 4

the amount of protons, electrons and neutrons

Question 5

what is a compound

Answer 5

two or more elements chemically bonded, formed by chemical reactions

Question 6

what are the different ways you can separate a mixture

Answer 6

chromatography,
filtration,
evaporation,
crystallisation

Question 7

what does chromatography do

Answer 7

separates out mixtures, usually liquids (eg colours in ink)

Question 8

what does filtration do

Answer 8

separates insoluble solids from liquids (eg sand and water)

Question 9

what does evaporation do

Answer 9

quickly separates soluble liquids from a solution

Question 10

what does crystallisation do

Answer 10

slowly separates a soluble salt from a solution (eg copper sulfate crystals)

Question 11

how do you calculate the number of neutrons

Answer 11

mass number (top) - atomic number (bottom)

Question 12

what does the relative atomic mass number show

Answer 12

the number of protons + neutrons

Question 13

which type of subatomic atom does the atomic number show

Answer 13

protons and electrons

Question 14

why are atoms neutral

Answer 14

because the number of protons and electrons are the same and one proton has a +1 charge and the electron has a -1 charge, meaning they cancel eachother out

Question 15

who discovered the plum pudding model

Answer 15

JJ Thompson

Question 16

who discovered atoms

Answer 16

john dalton

Question 17

what is the difference between the plum pudding model and the nuclear model

Answer 17

plum pudding has
ball of positives charge
no nucleus
no neutrons
evenly distributed mass

Question 18

who tested the plum pudding model?

Answer 18

ernest rutherford

Question 19

what did rutherford do in his experiment

Answer 19

fire positively charged alpha particles are gold foil

Question 20

what was the outcome of the alpha particles

Answer 20

most passed straight through = most of the atom is empty space
some deflected to the sides = particles had passed close by a positive charge
very small number repelled straight back = alpha particles had approached the nucleus straight on, this small amount showed him that the positive charge is in a very small dense core

Question 21

what (and when) did niels bohr discover

Answer 21

when = around 1911
what = electrons are in shells orbiting the nucleus

Question 22

what (and when) did James Chadwick discover

Answer 22

when = around 1940
what = neutrons in nucleus

Question 23

what does simple distillation do

Answer 23

separates a liquid from a solution
eg water from ink

Question 24

what happens during distillation

Answer 24

-liquid is heated to boiling point
-vapor travels up into the condenser
-condenser has cold water in it
-vapor cools down and condenses

Question 25

who created the first periodic table

Answer 25

john newlands

Question 26

what were the features of the first periodic table

Answer 26

-ordered by atomic weight -noticed a pattern with every eighth element -metals and non-metals grouped together -some elements didn’t fit the pattern -rejected by other scientists

Question 27

what was the name of the first periodic table

Answer 27

the ‘law of octaves’

Question 28

who discovered the second periodic table

Answer 28

dimitri mandeleev

Question 29

what were the features of mandeleeves periodic table

Answer 29

-still ordered by atomic weight -left gaps for undiscovered elements -could predict the properties of undiscovered elements -some elements didn’t fit the pattern ( switched to keep pattern of *similar* properties )

Question 30

why could elements not be ordered by atomic weight anymore?

Answer 30

because of the discovery of isotopes

Question 31

how is the modern periodic table ordered ?

Answer 31

by atomic number, columns/groups (vertical) rows/periods (horizontal)

Question 32

what does the period number represent (horizontal)

Answer 32

number of electron shells an atom has

Question 33

what does the mass number count

Answer 33

number of protons and neutrons

Question 34

what does the atomic number count

Answer 34

amount of protons or electrons

Question 35

what is an element

Answer 35

it is a substance in which all the atoms have the same atomic number

Question 36

what are the elements in the middle of the periodic table called

Answer 36

transition metals

Question 37

what is a molecule

Answer 37

two or more atoms bonded together

Question 38

atom

Answer 38

the smallest possible piece of an element has a radius of 0.1 nanometers (or 1x10^-10m)

Question 39

what is a mixture

Answer 39

at least two different elements or compounds together not chemically joined can be separated easily

Question 40

fractional distillation

Answer 40

used to separate a mixture of liquids with different boiling points

Question 41

another way of writing sodium chloride

Answer 41

NaCl

Question 42

another way of writing hydrochloric acid

Answer 42

HCl

Question 43

another way of writing ammonia

Answer 43

NH3 (small 3)

Question 44

another way of writing calcium chloride

Answer 44

CaCl2 (small 2)

Question 45

another way of writing sodium carbonate

Answer 45

Na2CO3 (small 2 and 3)

Question 46

another way of writing sulfuric acid

Answer 46

H2SO4 (small 2 and 4)

Question 47

how do you calculate the RAM fo an isotope

Answer 47

((isotope1 % / 100) x isotope1 mass) + ((isotope2 % / 100) x isotope2 mass)

Question 48

calculate the RAM of chlorine 25% Cl is Cl37 (small 37) 75% of Cl is Cl35 (small 35)

Answer 48

(25/100 x 37) + (75/100 x 35)

Question 49

what equipment is used in distillation

Answer 49

- thermometer - condenser - glass tube - mixture of two or more liquids - gas tube - circle bottomed flask - water in / water out

Question 50

What is chromatography?

Answer 50

separate components of a mixture

Question 51

What is the first step in chromatography?

Answer 51

The first step is the preparation of the sample.

Question 52

what are the pieces of equipment in chromatography

Answer 52

- pencil - strip of chromatography paper - beaker - spot of pigment - propapone

Question 53

the pigment that travelled the furthest is called the what?

Answer 53

solvent front

Question 54

the pigment that travelled the least far are less ____

Answer 54

soluble

Question 55

how does chromatography work

Answer 55

the solvent dissolves the pigment and carries them up the paper

Question 56

what happens when metals react?

Answer 56

they lose electron(s) and form positive ions

Question 57

what happens when non-metals react

Answer 57

they gain electron(s) and form a negative ion