OCR GCSE C4 Revision

When looking at the periodic table, Each row is a …………
period
When looking at the periodic table, each period starts with a very a………. ………. in group 1 and ends with an b…………. …….. in group 8

a reactive metal

b unreactive gas

When comparing the weights of atom, what do you use?
Relative atomic mass
When looking at the periodic table, what is a column called?
A group
Define a group
a group of similar elements

Give 5 properties of the alkali metals

1. They are soft – can be cut easily with a knife

2. They are very reactive

3. They are not very dense – they float on water

4. They have one electron in their outer shell

5. They react with water

When exposed to water, what do the alkali metals do?
React to form an alkaline solution and hydrogen gas.
Going down the group, do the alkali metals get more, or less reactive?
More reactive
Give 2 other names for energy levels

shells

orbits

What does the nucleas contain?

Protons (+)

Neutrons (no charge)

What do the energy shells contain?
electrons (-)
And atom is a……….. it has b…. overall charge

a neutral

b no

Number of protons =
number of electrons

complete the table

Energy levels        max. number of electrons

 1                             a……

2                             b……

3                             c……

4                             d……

                                                           

a 2

b 8

c 8

d the rest

Why are the alkali metals in group 1?
They all have 1 electron in their outer shells
Why is potassium more reactive than lithium and sodium?
Because the stray 1 elctron is in a higher energy level, meaning it’s easier to get rid of – it is further away from the pull of the nucleas.

How do the alkali metals try to get more stable?

By losing the stray 1 electron
Are the alkali metals good conducters of electricity?
yes
Do the alkali metals have a high melting point?
No, they melt on a very gentle heat
Most non-metals are ……
molecular (e.g. O2 ,;N2 )
All metals and C and Si are ………
atomic (e.g. Na, Mg, Fe)
Compounds of metals and no-metals are ………
salts
Many salts are ………………
crystalline

What happens when lithium (Li) is dropped into water?

It floats, fizzes gently and dissapears as it turns into Lithium hydroxide (LiOH). It makes an alkali solution as it dissolves. It also gives off hydrogen gas.

What happens when sodium (Na);is dropped into water?

The reaction gives out enough energy to melt the sodium, it skates around the surface. More vigorous than lithium.

;

Also produces sodium hydroxide (NaOH) and hydrogen.

What happens when Potassium (K) is dropped into water?

It floats and ignites with a lilac flame.

;

Also produces potassium hydroxide (KOH) and hydrogen.

How do you test for hydrogen?
Collect gas and use a burning splint. It will give a squeeky pop if it’s hydrogen.
Will all salts dissolve in water?
No, only some.
Will solid salts conduct electricity?

No, they must be dissloved first.

Does pure H2O conduct electricity?
No, it is the impurities in water that conduct electricity.
What is the flame colour of Sodium (Na)?
Yellow
What is the flame colour of Potassium (K)?
Lilac
What is the flame colour of calcium (Ca)?
Orange-red
What is the flame colour of barium?
Green
What is the flame colour of copper (Cu)?
Green
What is a flame spectra? Explain it.

When light given off by a flame is split into a spectrum, single pure colours can be seen.

 

Each element gives a unique flame spectra.

Why are flame spectra different for each element?

It’s due to the electrons. The heat gives them energy, they move up to higher energy levels. They then lose energy and fall to a lower energy level. They give out energy in the form of light.

;

Each atom has a different combination of ;jumps;, e.g. Hydrogen has 3 lines – 3 combinations of ;jumps;

What is each line on a spectra?

An electron falling down a level
more electrons = ?
more electrons = more lines in the spectra
How was helium discovered?
By analysing the spectrum of sunlight during an eclipse.
In a balanced equation, is there any mass change?

No, mass before = mass after

;;;;;;

Inter- means
between
Intra- means
within
What happens when Chlorine (Cl2) is exposed to iron and heated?

The iron wool must be heated initially, but one the reaction has started, heat from it keeps it going.

;

There is an instant, vigorous reaction. Clouds of iron chloride form. Little iron is left.

;

What happens when;Bromine (Br2) is exposed to iron and heated?
It must be heated throughout the reaction. The reaction is slower than with chlorine, and less reactive. The iron wool is coated with iron bromide. Some doesn’t react.
What happens when Iodine (I2) is exposed to iron and heated?

Strong heat is needed for a reaction. It’s slow to react and only a small amount does react. Iron iodite is formed.

Put the following in order of reactivity (most to least):

Bromine (Br2)

Iodine (I2)

Chlorine (Cl2)

;

;

Chlorine (Cl2)

Bromine (Br2)

Iodine (I2)

What is a danger of Chlorine (Cl2)?
It’s toxic
What are the dangers of Bromine (Br2)?
It’s toxic and corrosive
What is the danger of Iodine (I2)?
It’s harmful
List 3 properties of Chlorine (Cl2)

1. Dense, pale gas

2. Smelly and poisenous

3. occurs as chlorides, esp. sodium chloride in the sea

List 3 properties of Bromine (Br2)

1. Deep red liquid with red-brown vapour

2. Smelly and poisenous

3. Occurs as bromides, esp. magnesium bromide in the sea

List 3 properties of Iodine (I2)

1. Grey solid with purple vapour

2. Smelly and poisenous

3. Occurs as iodides and iodites in some rocks and in seaweed

Define soluble
can dissolve
Why won’t solid salts conduct electricity?
Solid salts are made of ions held in place in a ;giant ionis; structure. They are held in place, dissolve/melt them and they will be free to move, allowing a current to flow.
Define a cation
a positive (+) ion
Define an anion
a negative (-) ion

What happens when:

;;;;;; melt

Na+ Cl ———–>

         disolve

 

Na+          Cl

+ ion               -ion 

Cation                 Anion

Cations are attracted to the ……….
Cathode
Anions are attracted to the  ………..
Anode
Deinfe cathode
negative eletrode
Define anode
Positive electrode

At Cathode:

 

Na  +   e–   ——–>

Na

At Anode

 

Cl   ——–>

Cl + e

Why won’t solid compunds made of ions conduct electricity?
Because the ions are held in place. For charge to flow, the ions must be free to move.
Why do group 1 element need to lose 1 electron?
To have a full outer shell and be stable
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