3.1- Periodic Table Flashcards
1
Q
How many ways does the periodic table arrange elements in?
A
3
2
Q
How are elements arranged in the periodic table?
A
- by increasing atomic number
- in periods
- in groups
3
Q
What feature of atoms determines their reactivity?
A
The configuration of outer shell electrons
4
Q
Which elements are in the S block?
A
Element from groups 1 and 2
5
Q
Which elements are in the P block?
A
Elements in groups 3-7
6
Q
Which elements are in the d block?
A
Element between groups 2 and 3
7
Q
What is the definition of first ionisation energy?
A
The energy required to remove one mole of electrons from one mole of atoms in a gaseous state
8
Q
What is the general trend of first ionisation energy down a group?
A
It decreases
9
Q
Why does first ionisation energy decrease down a group?
A
- down the group, there is more shielding by the increase number of shells
- this also means the electron has a greater atomic radius and is further away
- this means there is a weekend traction between the nucleus and the electron, so it is easier to lose an electron
10
Q
Why does the first ionisation energy increase across periods 2 and 3?
A
- across a period, there is an increase in nuclear charge so the atomic radius decreases
- there is no addition of new shells to shield outer electrons
- therefore, there is a strong attraction between the nucleus and outer shell electrons so they are much harder to remove
11
Q
What is the general trend of first ionisation energy across periods 2 and 3?
A
It increases
12
Q
Do all atoms follow these general trends?
A
No, there are smaller trends which link to orbitals
13
Q
What can we use to work out the electron configuration of an unknown element?
A
Successive ionisation energies
14
Q
Why is there a big leap in successive ionisation energies between neon and sodium?
A
- Sodium is a group 3 element with 8 electrons in its outer shell
- Removing an electron from this full outer shell requires lots of energy
15
Q
What is the definition of second ionisation energy?
A
The amount of energy needed to remove one mole of electrons from mole of 1 + ions in a gaseous state
16
Q
What is the symbol equation for first ionisation energy, Element M?
A
M—->M+ +e-
including gaseous state symbols
17
Q
What three factors affect ionisation energy?
A
- Size of nuclear charge
- Amount of shielding
- atomic radius
18
Q
List two examples in period 3 which do not appear to follow the trend of successive ionisation energy increasing across a period.
A
Magnesium to aluminium
Phosphorus to sulphur
19
Q
Why does magnesium (group 2) have a greater ionisation energy than aluminium (group 3)? (not following the general trend)
A
- Aluminium has outer electron in the P orbital instead of the s orbital.
- A P orbital has higher energy so the electron is further from the nucleus
- This provides more shielding and even though there are more protons and hence a greater nuclear charge, the overall attraction is less so its easier to lose an electron
20
Q
Why does phosphorus have a higher ionisation energy than sulphur? (not following the general trend)
A
- In Phosphorus, an electron is being removed from singularly occupied orbitals but in sulphur, an electron is being removed from an orbital containing 2 electrons
- The repulsion between 2 electrons means that electrons are easier to remove from the shared orbital, so sulphur has a lower ionisation energy than phosphorus
21
Q
What is Periodicity?
A
Trends that occur in physical and chemical properties in the periodic table
22
Q
What is electronegativity?
A
The ability of an atom to attract the pair of electrons within a covalent bond to itself
23
Q
What is metallic bonding?
A
The strong attraction between the positive metal ions (cations) and the sea of delocalised electrons
24
Q
How would you draw a diagram of metallic bonding?
A
- positive metal ions labelled
- free floating electrons( different number depending on if they are ions)
25
What is a giant covalent lattice?
| What is an example of a giant covalent lattice?
A giant network of atoms all bonded covalently together
| Diamond, graphite and graphine
26
What are the three forms of carbon?
Diamond
Graphite
Graphene
27
Why do metal lattices have a high melting and boiling point?
The atoms are closely packed together with strong attractive forces between ions and electrons
Lots of energy is required to move these fixed ions which means that has a high melting and boiling point
28
Why are metal lattices a good conductor of electricity?
They have delocalised electrons which are free to move and carry current, even in solid state
29
Why do giant covalent lattices have a high melting and boiling point?
They have very strong covalent bonds throughout the structure which need to be broken before melting or boiling can occur
30
Do giant covalent lattices conduct electricity?
It varies, if there are free electrons they can conduct there are no free electrons they can't
31
Are giant covalent lattices soluble in water?
No, there are no ions to be solvated
32
Are metal lattices soluble in water?
No, they react with water instead
33
Ernesto says " melting points across period 2 and 3 will or a similar". Explain why ernesto is wrong
Melting points are dependent on the type of bonding within the atom, the number of electrons and if they form giant covalent lattices
34
Period 2 and 3 elements in groups 1,2 and 3 all have similar melting points. Explain why.
They all have a giant metallic structure with strong forces between the positive ions and delocalised electrons
35
Explain why group 4 elements in periods 2 and 3 have a high melting point
They have a giant covalent structure which requires lots of energy to break hence the high melting point
36
Explain why elements in group 5,6,7, and 8 in periods 2 and 3 have a low melting point.
They have a simple molecular structure and molecules are only linked by weak inter molecular forces hence the low melting point
37
What is an allotrope?
A different form of the same element in the same state
38
What type of ions do Group 2 elements form?
2 + ions
39
What is the general trend of reactivity down Group 2?
It increases
40
Why does reactivity decrease down Group 2?
- As you go down the group ionisation energy decreases due to increasing atomic radius and shielding
- With a lower ionisation energy, it's easier to lose electrons and hence easier to react
41
How do Group 2 elements react with water?
They react to give a metal hydroxide and hydrogen
42
How do Group 2 elements react when they burn in oxygen?
They react to produce solid white oxides
43
How to group 2 elements react with dilute acid?
They react to get a metal chloride and hydrogen
44
What is calcium hydroxide used for?
Neutralising acidic soil in agriculture
45
What is magnesium hydroxide and calcium carbonate used for?
Ingestion tablets as antacids
46
What colour is fluorine?
Pale yellow
47
What colour is chlorine?
Green
48
What colour is bromine?
Red-brown
49
What colour is iodine?
Grey
50
What is the general trend of boiling point down group 7?
It increases due to the increasing strength of the induced dipole dipole interactions
51
What is the general trend of reactivity down group 7?
It decreases
52
Why are group 7 halogens less reactive down the group?
Down the group, electrons are further from the nucleus and less strongly attracted
This makes it harder to gain an electron
53
If you react a more reactive halogen with less reactive halide solution, what type of reaction would occur?
A displacement reaction
54
Chlorine and potassium bromide react together. When mixed with cyclohexane, the less reactive halogen floats to the top layer. What colour will be on the top?
Orange
55
Bromine water and potassium iodide react together. What colour will the hexane layer be?
Purple
56
How can you identify which halogen or halide is present in a solution?
You carry out displacement reactions and see which halogens it reacts with
57
How can you test for halides?
1. Add dilute nitric acid to remove ions but might interfere with the test
2. Add silver nitrate solution and observe the precipitate formed
58
Tony carries out a halide test with silver nitrate and a white precipitate is formed. What halide ion is present?
Chloride Cl-
59
Tony carries out a halide test with silver nitrate and a cream precipitate is formed. What halide ion is present?
Bromine Br-
60
Tony carries out a halide test with silver nitrate and a yellow precipitate it is formed. What halide ion is present?
Iodine I-
61
What is a disproportionation reaction?
A reaction where a substance is simultaneously oxidised and reduced
62
How is household bleach formed? (equation)
2NaOH +Cl2 ---> NaClO + NaCl +H2O
| This is a dispropportionation reaction
63
What happens when you mix chlorine with water? (equation)
Cl2 + H2O hCL + HCLO
| Hypochlorous acid kills bacteria and makes it safe to drink
64
What are the benefits of chlorine in water treatment?
It kills disease causing microorganisms
Some chlorine remains in the water and prevents reinfection later on
It prevents the growth of algae, eliminating bad tastes and smells
65
What are the risks of chlorine in water treatment?
It can irritate the respiratory system and can cause severe Burns
Chlorine can react to form chlorinated hydrocarbons which are carcinogenic
66
An extremist is petitioning to have chlorine in water treatment banned. What could be the extremist logic?
There is no choice about having your water chlorinated. It is mass medication
(ethical concern)
67
What are the two alternative to chlorine in water treatment?
Ozone(O3)
| Ultraviolet light
68
Why is ozone not used more often in water treatment?
It's expensive to produce and it short half-life means treatment isn't permanent
69
How does ultraviolet light work in water treatment and why isn't it used more frequently?
It kills microorganisms by damaging their DNA, but it is ineffective in cloudy water and won't stop it being contaminated later on
70
What is the test for carbonate ions?
1. Add a dilute acid to your sample and Bubbles of gas produced through limewater
2. If the limewater Turns cloudy, then you know carbon dioxide is released and carbonate ions are present
71
What is the test for sulfate ions?
1. Add dilute hydrochloric acid and barium chloride solution
2. If a white precipitate (barium chloride) is formed, your mystery substance is a sulphate
72
Jeremy performs a halide test but is unsure of whether his precipitate is white or cream or yellow. What could Jeremy do next to be certain of his results?
Test the solubility of these precipitates in dilute and concentrated ammonia
73
Jeremy is testing for silver chloride with ammonia. What would he expect to see if chloride ions are present?
The silver chloride precipitate to dissolve in dilute ammonia and concentrated ammonia
74
Jeremy is testing for silver bromide with ammonia. Would he expect to see if the bromine ions are present?
The precipitate will dissolve in concentrated ammonia but not dilute ammonia
75
Jeremy is testing the silver iodide with ammonia. What would he expect to see if the iodine ions are present?
The precipitate does not dissolve in dilute or concentrated ammonia
76
Anthony thinks that he has produced some ammonia from an experiment. How can you test to be sure?
He can place damp red litmus paper in a test tube and see if the paper turns blue
77
Scarlet has a substance which contains an ammonium compound. How can Scarlet check that ammonium ions are present?
She can add sodium hydroxide to a substance and warm the mixture. She can then see if it turns damp red litmus paper blue.
78
Why is it important to perform all these tests for ions in a certain order?
Otherwise false positives may occur
79
What is an example of a false positive that can occur when testing for halide ions?
When testing for halide ions, you want to rule out the presence of sulfate ions first.
This is because sulphate ions or also produce a precipitate with silver nitrate.
80
What order should you perform your ion tests in?
Test for carbonates
Test for sulphate
Test for halide
81
Why should you add dilute acid to a solution before carrying out a ion test?
The acid will get rid of any locking anions that you don't want and help prevent false positive
