Flashcards in C4 Deck (44):
1
Which number tells you which element an atom is?
The proton (atomic) number
2
What happen to early attempts to find connection between the chemical properties of elements and their relative atomic masses?
They were dimissed by scientific community
3
Briefly outline the contribution that Doberiner made to the early development of the periodic table
In 1817 Johann Dobereiner proposed his ' law of triads'. He realised the relative atomic mass of the mass middle element in group in a group of three elements ( that had similar properties) was close to the average of the other two elements
4
Outline the contributions that Newlands made to the early development of the periodic table
He arranged the known elements in order of their atomic masses. He proposed a'law of octaves' meaning every eighth element had similar properties.This did not work for all the known elements , so was dissmied by the scientific community.
5
State the contributions that Mendeleev made to the development of the periodic table.
He put the known elements in order of relative atomic mass but left gaps for undiscovered elements. He also predicted what the properties of these undiscovered elements might be.
6
Why was Mendeleev's table ultimately more successful than had come before?
He put the known elements in order of relative atomic mass but left gaps for undiscovered elements. He also predicted what the properties of these undiscovered elements might be.
7
In terms of sub-atomic particles what do the relative atomic mass and the atomic number tell us?
The atomic number gives us the number of protons and electrons in an atom of an elements. The relative atomic mass tell us the number of protons +the number of neutrons
8
Where is a group in the periodic table?
A vertical column of elements
9
Where is a period in the periodic table?
A horizontal row of elements
10
Approximately where can metals and non metals be found on the periodic table?
Metals on the left and in the middle, non-metals on the right
11
What are the group 1 elements also known as?
The alkali metals.
12
Describe the appearance of the group 1 metals when they have been freshly cut.
They are silver and shiny.
13
What happens to the group 1 metals when they are exposed to air? Why is this?
They tarnish and become dull due to reacting with moisture and oxygen in the air
14
Describe the reactions of lithium, sodium and potassium in cold water.
All the alkali metals react vigorously with cold water. In each reaction, hydrogen gas is given off and meal hydroxide is produced.
15
What is the reaction of lithium and water?
Lithium + water =lithium hydroxide + hydrogen
16
What is the symbol equation for sodium reacting with water?
2Na(s) + 2H2O (I) = 2NaOH(aq) + H2 (g)
17
Alkali metals react vigorously with chlorine. Describe the appearance and formula of the product formed.
A colourless, crystalline salt is formed with the formula MCl ie LiCl or KCl
18
Give an example of show that the alkali metals become more reactive as the group it descended.
In their reactions with water, the reactions become increasingly vigorous as you go down the group.
19
State and explain one precaution necessary when working with group 1 metals and alkalis.
Strong alkalis are corrosive , so care must be taken when they are in use for example by using goggles and gloves
20
Identify the states and appearances of chlorine , bromine, and iodine at room temperature and pressure.
Chlorine = green gas
Bromine = reddish-brown liquid
Iodine = Dark-purple
21
Halogens consist of diatomic molecules: what does this mean?
It means the element exist as molecules of twos
22
Describe the reactivity of the halogens as the group descends. Give an example to show this.
The reactivity of the halogens decreases as we move down the group. This can be shown by looking at displacement reactions. For example, When chlorine is added to sodium bromide solution , the chlorine takes the place of the bromide, Because chlorine is more reactive than bromine. This make it sodium chloride.
23
How can the trend in reactivity for halogens be demonstrated by displacement reactors?
The most reactive halogen displaces all the other halogens from the solution of their salts, and is itself displaced by none of the others. The least reactive halogen displaces non of the others and is itself displaced by all the others
24
State and explain the safety precautions necessary when working with halogens
Because the halogens are very reactive and poisonous, car must be taken when using them. Chlorine is only used in a fume cupboard. Iodine should not be handled ( it will damage skin) Gloves may be used and goggles should be worn
25
Describe the general structure of an atom.
Protons and neutrons in a very small central nucleus with electrons arranged in shells around the nucleus.
26
Recall the relative masses and charge of protons, neutrons and electrons.
Protons; mass = 1 ; charge = 1 +
Neutron; mass = 1 ; charge = 0
Electron; mass = negligible; charge = 1-
27
In an atom what are there equal numbers of ?
Electrons and protons
28
All atoms of the same element have the same number of what?
Protons
29
Elements in the periodic table are arranged in order of what?
Proton number
30
What happens to some elements Eg lithium and potassium, when heated ?
They emit distinctive flame colours
31
Why did the study of line spectra help chemists to discover new elements?
Because each element has individual, characteristics line spectrum.
32
How did the development of new practical techniques such spectroscopy aid the development of science?
It helped scientists discover new elements
33
Describe how you can use the periodic table to work out the number of protons , electrons and neutrons in an atom.
Proton number is the same as the atomic number
Electron number is the same as the atomic number
Neutron number is the mass number minus the atomic number
34
In terms of electrons and shells, what happens across a period?
The same shell fills up with electrons a period
35
In terms of electrons and shells, what happens down a group?
The element in the same group have the same number of electrons in their outer shell ( this is the same as the group number) but they all have different umber of shells
36
What determines the chemical properties of an elements ?
Its electron arrangement
37
What is the fact that molten compound of metals with non-metals conduct electricity evidence for?
It shows that they are made up of charged particles (called ions)
38
What is an ion?
An atom that has gained or lost an electrons and has an overall charge
39
Identify and explain the charge on the ions of group 1 elements?
Group 1 atoms form 1+ ions because they lose one electron in order to have a full outer shell of electrons
40
Identify and explain the charge on the ions of group 7 elements?
Group 7 elements form 1- ions because they gain one electron in order to have a full outer sell of electrons
41
what is the type of bonding in the compounds formed from group 1 and group 7 elements?
Ionic bonding
42
Solid ionic compounds form crystals, why?
Because the ions are arranged in a regular lattice .
43
What happens to the ions when ionic crystals melt or dissolves in water?
The regular crystal lattice breaks down into positive and negative ions that are free to move.
44