Halogens exists as diatomic molecules. but Why
Each atomss needs one more decton to come stable. Each atom does this by sharing one electron to form a single covalent bond
do the halogens conduct electricity
no, they are non-metals
True or false. The halogens are posonousa and coloured
True, darker in colour as you go down the group
What are the physical properties of halogens
Brittle and cumble as solids
In groups 1 and 7 what happens to reactivity
Group 7 reativity decreases as you go down the group
Group 1reactivity increases as you go up
antoine lavoiser made a different periodic table and put them into 4 groups. Name 2 elements that aare not on ours today
heat and light
what year did antoine lavoiser change the periodic table
1789
When did Mendeleev make his version of the periodic table
1869-1871
Mendeleev periodic table:
what did he list them in
periods and groups
Mendeleev periodic table: what did he put the elements in order by?
Atomic Mass. Also by characteristics
Mendeleev periodic table: what did he do if there was a big gap in data
left gaps if he thought an element hadnt been discovered
Where was Mendeleev from
russia
why do atoms of elements gain or lose electrons?
to have a full outer shell
what do atoms become after they have a full outer shell
stable
what determines the position of an element on the periodic table
atomic number
what are group 1 called
alkali metals
what are 3 of the grp 1 elements
lithium, sodium and potassium
How many electrons in the outer shell of the grp 1 elements
1
Do grp 1 elements lose or gain an electron when they react
lose one to get a full outer shell and beomce stable
Do grp 1 elements for positive or negative ions
positive
Do grp 7 elements for molecules
yes
How would grp 7 elements react
a more reative halogen would displace a less reactive one, from the solution of itself
what are the horizontal lines on the periodic table
periods
what are the 5 original elements in grp 7
Flurine Chlorine bormie iodine and astaline
Who ordered 36 elements
John Dalton
what year were elements ordered by John Dalton
1808
What did John Dalton give each element
A symbol, but this was later discarded
Where the symbols John Dalton gave elements easy to remember
no
What are the properties of the group 1 elements
Soft, shiny, east to cut, silvery coloured metals
how reactive are group 1 elements
They are highly reactive
Are there any trends in the reactivity of group 1 elements
Yes, the reactivity increases as you go down the group. Lithium is least reactive and Francium is the most reactive.
Do group 1 elements have high or low melting points
low
Do group 1 elements have high or low density
how must you store group 1 elements and why
in oil so they do not react with the oxygen in the air
what happens to the silvery shiny service of group 1 elements when they ract with oxygen and why
they quickly go dull as a layer of oxide is formed on the shiny surface
describe the burning of alkali metals in a jar of oxygen
the hot alklai metals burn vigorously, forming white smoke of their oxides
describe the chemical equation of the formation of oxide on group 1 elements
what sort of compounds do group 1 elements form
Always ionic compounds
how do lithium, sodium and potassium react to water and why (colour of flame for potassium etc)
The metal floats moving and fizzing: the metal reacts with the water to form hyydrogen gas. potassium reacts so vigorously with the water that the hydrogen produced ignites. It burns with a lilac flame, coloured by the potassium ions formed in the reaction.
The reaction between an alkali metal and water also produces a metal hydroxide. This is why they are called alkali metals. The hydroxides of the alkali metals are all soluble in water. The solution is colourless with a high pH. (Universal indicator turns purple.)
All of the hydroxides of alkali metals aresoluable in water what is the colour, pH and what colour does the solutiuon tern universal indicator paper?
solution is colourless with a high pH. Purple
What happens to the Group 1 metals get lower
they get lower and lower
descrbe balanced symbol equation for sodium plus water and potassium plus water
describe balanced symbol equation for sodium reation with chorline
A metal chloride is produces which is a white solid that dissolves readily in water to fomr a colourless solution
where are the reactive metals in the periodic table
left
where are the transition metals in the periodic table
middle
where are the non-metals in the periodic table
right
what determines an elements properties
number of electrons in its outer most shell
Explain the reactivty trend within groups
As you go down a group in the periodic table, the number of shells occupied by electrons increases, by one extra electron shell per period.
This means that the atoms become larger going down any group.
This has two effects:
larger atoms lose electrons more easily going down a group
larger atoms gain electrons less easily going down a group.
This happens because the outer electrons (which are negatively charged) are further away from the attractive force of the nucleus (which is positively charged because of its protons). Also, the inner shells of electrons 'screen' or 'shield' the outer electrons from the positive charge of the nucleus. You can see this effect with the alkali metals and the halogens. Remember that the atoms of alkali metals tend to lose electrons when they form chemical bonds. On the other hand, the atoms of the halogens tend to gain electrons.
Trends Key points
You can explain trends in reactivity as you go down a group in terms of the attraction between electrons in the outermost shell and the nucleus.
This electrostatic attraction depends on:
the distance between the outermost electrons and the nucleus
the number of occupied inner shells (energy levels) of electrons, which provide a shielding effect
the size of the positive charge on the nucleus (called the nuclear charge).
In deciding how easy it is for atoms to lose or gain electrons from their outermost shell, these three factors must be taken into account. The increased nuclear charge, due to extra protons in the nucleus, going down a group is outweighed by the other two factors.
Therefore electrons are easier for the larger atoms to lose going down a group, and harder for them to gain going down a group.
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