the periodic table

Question 1

before the 20th century, what could scientist measure regarding elements

Answer 1

relative atomic mass

Question 2

what was noticed after arranging elements in order of mass

Answer 2

properties of elements where repeated at regular intervals

Question 3

what are some problems with the early periodic tables

Answer 3

not all elements had been discovered so not compleate

ended up in the wrong group as they where placed in order of relative atomic mass

Question 4

what did Dmitri Mendeleev do

Answer 4

1869
left gaps
mainly in order of atomic mass
but switched order of some elements
so elements with the same properties ended up in the same groups
the gaps allowed predictions to be made about undiscovered elements

Question 5

what did the discovery of isotopes do

Answer 5

isopotops of the same elemnt have different atomic masses but the same chemical propeties so occopy the same place on the pt so mendeelev was right to leave gaps

Question 6

what is the modern periodic table measured in

Answer 6

incresing atomic number

Question 7

what does the period number tell you

Answer 7

how many electron shells

Question 8

what does the group number tell you

Answer 8

how many electrons in the outer shell

Question 9

what are metals

Answer 9

elements that form positive ions when they react

Question 10

why cant non metals form positive ions

Answer 10

right of pt where they have lots of electrons to remove gto form a full outer shell or near the top where the outer shell elecrons have a strong force of attraction towards the nucleus.

Question 11

physical properties of metals

Answer 11

strong
malible
great conductors of heat and elecricty.
high boiling and melting points.

Question 12

physical properties of non metals

Answer 12

dull
brittle
lower bp and mp
lower density

Question 13

what are the alkali metals and what are their properties

Answer 13

group 1: lithium, sodium, potassium, rubidium, caesium and francium

they are silvery solids that have to be kept in oil.
one elecron in their outer shells. low density and get more reactive down the group

Question 14

why do alkali metels get more reactive down the group

Answer 14

elecron is further away from force of attraction of the nucleus

Question 15

what happens to the boiling point going down group 1 elements

Answer 15

decreases down the group

Question 16

what do the alkali metals make when they react with non metals

Answer 16

ionic compounds with a positive 1 charge.

the compounds are usually white solids that dissolve in water to form colourless solutions.

Question 17

what is the equation for the reaction of alkali metals with water

Answer 17

alkali metal + water = metal hydroxide + hydrogen

Question 18

why are the group 1 metals called alkali metals

Answer 18

the hydroxides formed when will dissolve in water to create alkali solutions

Question 19

what is the equation for the reaction of alkali metals with chlorine

Answer 19

metal chlorine

its white

Question 20

what is formed when alkali metals react with oxygen

Answer 20

metal oxide

Question 21

what elements are the halogens

Answer 21

Florine , chlorine, bromine, iodine and astatine

Question 22

how do the halogens exist in their natural state

Answer 22

in pairs

Question 23

halogens are metals that have what coloured vapours

Answer 23

fluorine - poisonous yellow gas
chlorine - poisonous dense green gas
bromine - poisonous dense red brown volatile liquid or orange vapour
iodine - poisonous dark grey crystalline solid or purple vapour

Question 24

what are the reactivity trends in the halogens

Answer 24

less reactive going down the group
because they react by gaining an electron
the outer shell is further away from the nucleus moving down the group so there is a smaller force of attraction from the nucleus

Question 25

what is the boiling point trend for the halogens

Answer 25

increase down the group

Question 26

what and how do halogens react with other non metals

Answer 26

other non metals
covalent bonds
the compounds formed have simple molecule structures

Question 27

what are formed when a halogen reacts with a metal

Answer 27

halide ions

Question 28

what do halogens do in displacement reactions

Answer 28

a more reactive halogen will displace a less reactive halogen from an aqueous solution of its salt

Question 29

name 3 noble gasses

Answer 29

helium, neon, argon

Question 30

why are the noble gasses inert

Answer 30

full outer shell of electrons

Question 31

what do noble gasses look like

Answer 31

colourless monatomic gases (single atoms not bonded)

Question 32

why does the boiling point of noble gasses increase going down the group

Answer 32

going down the group atomic number increases so there are more electrons which causes the intermolecular forces between the atoms to increase

Question 33

what are some properties of transition metals

Answer 33

good conductors of heat and electricity, dense, strong, shiny

Question 34

compare transition metals with alkali metals

Answer 34

tm are less reactive
tm are denser, stronger and harder
tm have much higher melting points

Question 35

why do transition metals form coloured compounds

Answer 35

due to the tm ion they contain.
e.g potassium chromate is yellow
potassium manganate is purple

Question 36

do transition metals make good catalyst

Answer 36

yes