chemistry

Question 1

what’s the relative mass of a neutron

Answer 1

1

Question 2

what’s the relative mass of a proton

Answer 2

1 m/u

Question 3

what’s the relative mass of an electron

Answer 3

1/2000

Question 4

why are the elements in group 0 unreactive

Answer 4

they have a stable arrangement of electrons (full outer shell)

Question 5

name two differences between newlands periodic table and the modern one

Answer 5

(no group zero.)
(the halogens are in group one)
the transition metals are in groups
hydrogen is in a group

Question 6

why did mendeleev change the order of some of the elements when developing his periodic table

Answer 6

some of the elements appeared to be in the wrong group when the elements were arranged in order of relative atomic mass so he placed them into groups with similar properties

Question 7

why are the elements ordered differently in the modern periodic table

Answer 7

most elements are mixtures of isotopes so should be arranged in order of atomic mass

Question 8

what’s the size of a prokaryotic cell

Answer 8

0.1 - 5.0 micrometers in diameter

Question 9

what’s the size of a eukaryotic cell

Answer 9

10 to 100 micrometers

Question 10

how does the diameter of the atom effect the reactivity of group one elements (4 marker)

Answer 10

as the diameter increases, the reactivity increases because as the diameter increases the outer electron is further from the nucleus so the outer electron is less attracted to the nucleus so the outer electron is lost more easily

Question 11

why do atoms have an overall neutral charge

Answer 11

protons are positive and electrons are negative and theree are the same number of each in an atom. therefore the opposite charges cancel out to make no overall charge

Question 12

what’s the equation for the reaction of potassium with water

Answer 12

2K + 2H2O + 2KOH + H2

Question 13

why is oxygen described as reduced in the reaction between sodium and oxygen?

Answer 13

because oxygen gains electrons

Question 14

why does sodium oxide have a high melting point (3)

Answer 14

it has a giant structure with strong electrostatic forces of attraction between oppositely charged ions so large amounts of energy are needed to break the forces

Question 15

what is an isotope?

Answer 15

an atom with the same proton number but different numbers or neutrons

Question 16

give two reasons why the discovery of gallium six years after the publish of mendeleev’s periodic table helped the table become more accepted

Answer 16

1 - gallium fitted a gap that mendeleev left

2 - the properties were predicted correctly

Question 17

what’s the name of elements in group 0

Answer 17

noble gases

Question 18

what increases down group 0

Answer 18

boiling points

Question 19

what type of particles are in a sample of neon?

Answer 19

atoms

Question 20

what is the type of bonding in sodium?

Answer 20

metallic

Question 21

give two ways in which the observations of alkali metals with water reactions show change in reactivity down group 1

Answer 21

1 - increasing rate of bubble production

2 - increasing speed of movement

Question 22

out of diamond , magnesium, poly(ethene), sodium chloride and water which two substances have intermolecular forces between particles?

Answer 22

poly(ethene) and water

Question 23

atoms were first thought to be tiny spheres that could not be divided

what particle was this

Answer 23

electron

Question 24

what type of particle was fired at gold atoms to discover the new model of the atom

Answer 24

alpha particles

Question 25

which scientist suggested that electrons orbit the nucleus at specific distances

Answer 25

bohr

Question 26

what scale matches 1 x 10^-2

Answer 26

a sports arena of radius 100m

Question 27

name three differences between the nuclear model and plum pudding model

Answer 27

in the plum pudding model, the atom is a ball of positive charge the nuclear model is mostly empty space in the nuclear model, the electrons and nucleus are separate

Question 28

describe the change that niels bohr made to the nuclear model

Answer 28

electrons orbit the nucleus electrons are at specific distances from the nucleus

Question 29

which particle has the lowest mass

Answer 29

electron

Question 30

what is mass number

Answer 30

number of protons plus number of neutrons

Question 31

james chadwick proved the existence of the…

Answer 31

neutron

Question 32

what is the test for chlorine gas

Answer 32

damp litmus paper turns white

Question 33

describe what happens when sodium reacts with fluorine to produce sodium fluoride

Answer 33

sodium loses one electron fluorine gains one. an ionic bond is formed

Question 34

what are two properties of ionic substances

Answer 34

dissolve in water high melting point

Question 35

why does pure water not conduct electricity

Answer 35

there’s no delocalised electrons

Question 36

going down group 7….

Answer 36

the melting points increase because the size of the molecules increases so the intermolecular forces increase

Question 37

is chlorine gas coloured, flammable or toxic

Answer 37

toxic

Question 38

why does the mass increase in the reaction iron + chlorine —> iron chloride

Answer 38

because chlorine atoms are now a part of the solid (iron chloride)

Question 39

what’s the modern name for atomic weight

Answer 39

relative atomic mass

Question 40

how are elements arranged in the modem periodic table

Answer 40

in order of increasing atomic number

Question 41

give two differences between properties of iron and sodium

Answer 41

iron has higher boiling point and iron is less reactive - iron is denser - iron is stronger - iron is harder

Question 42

why can carbon be used to extract nickel from nickel oxide

Answer 42

carbon is more reactive so will displace nickel

Question 43

why does iron not belong in a group with oxygen and sulfur

Answer 43

iron is a metal

Question 44

why did mendeleev leave gaps for undiscovered elements

Answer 44

so that elements with similar properties could be placed together

Question 45

why are lithium sodium and potassium all in group one

Answer 45

all have one electron in the other shell so they have similar properties

Question 46

covalent bonding takes place between…

Answer 46

non metals

Question 47

ionic bonding takes place between

Answer 47

metals and non metals

Question 48

what is ionic bonding

Answer 48

ionic bonding is the transfer of electrons from one atom to another to form oppositely charged ions. strong electrostatic forces hold these ions together

Question 49

what is metallic bonding

Answer 49

positive metal ions are arranged regularly with a sea of delocalised electrons. the strong electrostatic forces of attraction hold the structure together