How was Dalton's periodic table ordered?
The table was based on the atomic weights of elements.
How was Newlands' periodic table (1963) ordered?
Newlands' table put the elements in order of atomic weight, but he also proposed his 'Law of Octaves'.
This was based on his observations that every 8th element had similar properties.
He put the 62 elements known at the time into 7 groups, but after calcium the pattern broke down, so there was not enough evidence for other scientists to accept his ideas.
Why was Mendeleev's table (1969) better than Newlands' table?
Mendeleev provided the basis for the modern periodic table.
Mendeleev's left gaps for the unknown elements and swapped some atomic weights around.
Mendeleev even predicted the properties of the missing elements.
What determines an element's position in the modern periodic table?
The atomic (proton) number.
What determines an element's chemical properties?
The number of electrons on the outer shell.
What is the group number?
The group number equals the number of electrons in the outer shell.
As we go down a group the reactivity in metals...
Why do metals get more reactive going down a group?
As the atoms get larger there are more occupied energy levels so the outer electron(s) is/are further from the nucleus so there is less electrostatic attraction.
This means it is easier for the larger atoms to lose their atoms to lose their outer electron(s).
As we go down a group the reactivity in non-metals...
Why are Group 1 elements called alkali metals?
Because they react with water to make an alkali solution containing the metal hydroxide.
What is the physical description of all Group 1 elements?
What is the word equation for the reaction of sodium with water?
Water + Sodium ➝ Hydrogen + Sodium Hydroxide.
What is the reactivity trend of Group 1 elements?
Going down Group 1, the reactivity increases.
What do Group 1 elements form when they've reacted with Group 7 elements?
Salts that are white or colourless crystals.
Where are the transition elements found in the periodic table?
In the middle, between groups 2 and 3.
How are transition metals different to the elements in Group 1?
Compared with the alkali metals, transition elements have much higher melting points and densities.
They are also stronger, harder and much less reactive.
What are Group 7 elements also known as?
What colour is Fluorine vapour?
What colour is Chlorine vapour?
What colour is Bromine vapour?
What colour is Iodine vapour?
What is the reactivity trend of Group 7 elements?
Going down Group 7, the reactivity decreases.
Why would Chlorine displace Bromine?
Because it is more reactive.
...Pair up. e.g: F2, Cl2.
What is a halide?
A compound containing a Group 7 ion.
How can presence of iodine be tested?
With starch, which turns iodine dark in colour.
Are halogens coloured, or halides?
Halogens are coloured, Halides are not coloured.
Give the ionic equation for this full equation.
F2 + 2KCl ➝ 2KF + Cl2.
F2 + 2Cl- ➝ 2F- + Cl2.