Chemistry- the periodic table

Question 1

What did Mendeleev do differently to Newland?

Answer 1

He left gaps for undiscovered elements and moved some elements around

Question 2

How did Mendeleev justify changing some element’s positions?

Answer 2

He said previously the data was badly measured!

Question 3

Why did scientists dislike Newland’s theory of “the law of octaves?”

Answer 3

-why do it according to a piano of all things?
-two elements in some boxes
-he didn’t explain it

Question 4

what are the modern versions of eka-silicon and eka-aluminium? (respectively)

Answer 4

germanium and gallium

Question 5

Give two important differences between Mendeleev’s and the modern periodic table

Answer 5

-Elements are ordered due to atomic number, not mass
-no noble gases
-there are more groups- transition metals- ih the modern table

Question 6

What is the definition of atomic mass?

Answer 6

The relative weight of each element, compared to carbon

Question 7

What is the trend with softness in g1 metals?

Answer 7

they get softer to cut further down the group- and they’re quite easy to cut in the first place

Question 8

What is the trend in density in g1 metals?

Answer 8

all are not very dense- top three can float on water, and density generally increases down the group

Question 9

What is the trend in melting point in g1 metals?

Answer 9

low- Li (181) -> Cs (28)
They get lower because the ions get weaker, and the free electrons are further away from the positive nuclei

Question 10

What five things would you see when you put a g1 metal in water?

Answer 10

-fizzing
-spits, flares or flame
-sodium + potassium melt
-float
-move around surface

Question 11

What is the trend in reaction in g1 metals? (and why?)

Answer 11

more reactive down the group. As the atoms get larger the outer shell electron gets further away from the positive protons in the nucleus, meaning there are weaker forces between them and the electron is easier to lose

Question 12

give four common features of g1 compounds

Answer 12

ALL ARE:
white (solids), soluble, ionic, colourless (solutions)

Question 13

REMEMBER: all halogens are…

Answer 13

diatomic

Question 14

What is the colour and state of fluorine at room temperature?

Answer 14

pale green gas

Question 15

What is the colour and state of chlorine at room temperature?

Answer 15

pale yellow gas

Question 16

What is the colour and state of bromine at room temperature?

Answer 16

red/brown liquid

Question 17

What is the colour and state of iodine at room temperature?

Answer 17

grey solid

Question 18

What is the colour and state of astatine at room temperature?

Answer 18

black solid

Question 19

What is the colour of fluorine solution?

Answer 19

colourless

Question 20

What is the colour of chlorine solution?

Answer 20

v.pale green

Question 21

What is the colour of bromine solution?

Answer 21

orange

Question 22

What is the colour of iodine solution?

Answer 22

brown

Question 23

What is the colour of iodine gas?

Answer 23

purple

Question 24

What is the trend of reactivity in halogens and why?

Answer 24

less reactive down the group- it is harder for the halogens to gain an electron as there is a larger distance between the +ve nucleus and -ve electron being gained

Question 25

What is the trend of melting points in halogens and why?

Answer 25

higher down the group-
larger atoms, stronger IMF, harder to break
no bonds are broken.

Question 26

what does OIL RIG stand for?

Answer 26

Oxidation
Is
Loss (of electrons)
Reduction
Is
Gain (of electrons)

Question 27

does the O in Oil Rig have anything to do with the element oxygen?

Answer 27

No

Question 28

In the equation 2Al + Cl2 -> 2AlCl3, which element has oxidised and which has reduced?

Answer 28

Al- oxidised (has lost electons, as it is a metal)
Cl- reduced (has gained electons, as it is a non-metal)

Question 29

what do half-equations have that normal equations don’t?

Answer 29

electrons

Question 30

do covalent/ionic molecules split up when they dissolve?

Answer 30

covalent: no
ionic: yes

Question 31

What is the trend for boiling point and density in noble gases?

Answer 31

increase down the group

Question 32

Why do the boiling points of noble gases increase (in whichever direction?)

Answer 32

as the atoms get larger, imf increase

Question 33

why does helium not react?

Answer 33

There are no gaps in the outer shell, so it is stable and does not need to gain/lose/share electrons

Question 34

why were noble gases undiscovered for much of history?

Answer 34

low abundance, little reactions, colourless gases

Question 35

List some uses (and reasons) for uses of Helium

Answer 35

airships, balloons- low density
diving- does not dissolve in blood

Question 36

List some uses (and reasons) for uses of Neon

Answer 36

lights- glows when a current is charged through

Question 37

List some uses (and reasons) for uses of argon

Answer 37

filament light bulbs- protects wire from reacting w/ O2 or N2

Question 38

List some uses for uses for krypton and xenon

Answer 38

lasers

Question 39

List some reasons why we don’t use radon

Answer 39

radioactive- causes cancers and other health problems

Question 40

Why do elements in the same group undergo similar reactions? **

Answer 40

-chemical reactions depend on outer shell electrons
-elements in the same group have the same number of outer shell electrons

Question 41

What should you remember when doing “Which element is in Group X and Period Y” questions? **

Answer 41

Don’t count transition metals!

Question 42

What should you remember when doing reaction questions? **

Answer 42

diatomic gases

Question 43

You are given KCL, CL2, KBr, Br2, KI, I2. Prove that iodine is less reactive than bromine using the word “oxidise” **

Answer 43

-Add Br2 to KI
-colour change: orange-> brown
-iodine was oxidised by bromine
-iodine must be less reactive than bromine