The Law of Ocataves which stated that similar properties are repeated every eighth element.
1 of 26
Wh did scientists in the 19th century use atomic weights rather than proton numbers to classify elements?
Protons (and electrons) had not been discovered or the atomic structure was not discovered
2 of 26
Why did scientists reject Newlands idea?
After calcium, the properties of the elements did not match within the groups.
3 of 26
What was Mendeleev's proposed idea?
Produced a table which left gaps for elements that had not been discovered so that all properties in a group matched.
4 of 26
What are the similarities in their work?
Both ordered elements according to the their atomic weight and attempted to match properties within a group.
5 of 26
What were the differences between their work?
Mendeleev left gaps for the undiscovered elements, whilst Newlands included all the elements known. Newlands kept a strict order of the atomic weights whilst Mendeleev swapped them around. One was accepted, one wasn't.
6 of 26
Why do elements have similar chemical properties?
They have the same number of electrons on their highest occupied level.
7 of 26
How are elements arranged in a periodic table?
In order of their atomic numbers and are lined up in vertical groups.
8 of 26
What happens to the attraction and size of an atom as we go down the group?
Atoms get larger which means that the attraction between the nucleus and electrons in the highest occupied level becomes weaker.
9 of 26
Why metals get more reactive as we go down the group?
As atoms get larger there are more occupied energy levels and the electrons in the highest occupied energy level are less attracted to the nucleus so are lost more easily.
10 of 26
Why are elements in group 1 called alkali metals?
They react with water to form alkalis or their hydroxides are alkalis.
11 of 26
State the six properties of the alkali metals.
1. Low melting and boiling points 2. Low densities 3. They react with water to create hydrogen gas and a metal hydroxide which is an alkali. 4.+ 1 ions 5. Form salts when reacted with group 7 6. Dissolve colourless solutions.
12 of 26
Sodium and Chlorine react together to make...
Sodium chloride
13 of 26
Potassium and Bromine react together to make...
Potassium Bromide
14 of 26
Explain the reactivity trend in Group 1
As more electrons occupy the highest energy levels, the reactivity of group 1 increases because there is a weak attraction between the nucleus and the highest electron so this is easily lost.
15 of 26
Why is lithium less reactive the sodium?
Lithium is a smaller atom than sodium so the electrons are strongly attracted the nucleus.
16 of 26
what groups are the transition elements found in?
Group 2 and 3
17 of 26
Why are the transition elements useful as building materials?
They are strong and dense, and mainly used as alloys in building materials. React slowly with oxygen and water.
18 of 26
State the 8 properties of transition metals
1. Higher m.p.t and b.p.t than alkali metals 2. Malleable and Ductile 3. Conductors of heat and electricity. 4. React slowly with oxygen and water 5. Strong and dense 6. Form positive ions with various charges. 7.Compounds and colourful. 8. Catalysts
19 of 26
How are transition metals different to alkali metals?
Higher melting and boiling points, stronger, harder, denser react slowly with oxygen and water, ions have various charges, coloured compounds and catalysts
20 of 26
Why do halogens have low melting and boiling points?
They have small molecules (made up of pairs of atoms)
21 of 26
State the 5 properties of halogens
1. Low m.p.t and b.p.t 2.At room temp they are gases and liquids except iodine. 3. 7 electrons on highest level 4. -1 halide 5. Bond covalently to form moelcules
22 of 26
At room temperature what colour and state is fluorine and chlorine?
Fluorine is a pale yellow gas and Chlorine is a green gas
23 of 26
What Iodine transition to and from?
Iodine can transition to a violet vapour from a grey solid state
24 of 26
How could you show chlorine is more reactive than bromine?
Add chlorine to a solution of potassium bromide and bromine will be displaced.
25 of 26
Explain the reactivity trend in Group 7.
The reactivity of the halogen decreases going down the group. This is because the attraction of the outer electrons and the nucleus is weaker as the atoms get larger, which means it is harder to gain an electron.
26 of 26
Other cards in this set
Card 2
Front
Wh did scientists in the 19th century use atomic weights rather than proton numbers to classify elements?
Back
Protons (and electrons) had not been discovered or the atomic structure was not discovered
Comments
No comments have yet been made