IO1: Periodicity Flashcards

1
Q

In terms of the periodic table, where are the blocks found?

A

s- left
d- middle
p- right
f- bottom

(outer electrons in these orbitals)

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2
Q

Do groups or periods have similar chemical properties?

A

Groups

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3
Q

Periods are arranged…

A

Periodically, as they have repeating patterns or periodic trends

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4
Q

In terms of the periodic table, where are metals and non-metals?

A

Metals- left and middle until the…
Metalloids- diagonal B, Si, As, Te, At, separates metals and non-metals
Non-metals- right

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5
Q

What is a metalloid?

A

Show some chemical properties of a metal, but is not a metal.

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6
Q

What is the trend in atomic radius of group 2?

A

Increases down

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7
Q

What is the trend in 1st ionisation energy of group 2?

A

Decreases down

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8
Q

How do the group 2, alkaline earth metals bond?

A

Metallically

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9
Q

What state are the group 2 metals at room temp?

A

Solid

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10
Q

What is the trend in melting point of group 2 metals?

A

Decreases down

-Metallic bonds get weaker
-Apart from Magnesium, which is lower than all group 2 metals

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11
Q

How do the group 2 metals react with water?

A

Going down, each reacts more vigourously.

-This is because 1st IE decreases down the group, so easier to lose electrons (decrease activation energy)

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12
Q

Which group 2 metal does not react with water?

A

Be

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13
Q

How does Mg react with water?

A

Only slightly, but does rapidly react with steam and gives off a bright light.

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14
Q

Group 2 + water =?

A

Metal Hydroxide

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15
Q

Magnesium can be used to extract Ti from its ore, explain how.

A
  1. TiO2 is heated with carbon and chlorine to form titanium chloride
  2. Reduced by Mg where Mg donates its electrons to Ti, making Ti and magnesium chloride.

Mg= reducing agent

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16
Q

How is calcium used to prevent acid rain?

A

Burning fossil fuels gives off SO2 which causes acid rain.

-Spraying ‘slurry’ of calcium carbonate, or calcium oxide over sulfur dioxide gas, and collects the calcium sulfide that forms.

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17
Q

What is the solubility of Group 2 Hydroxides?

A

Increases down the group

Magnesium hydroxide is hardly soluble, so is a white precipitate

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18
Q

What group 2 hydroxide can be used to cure heartburn and why?

A

Magnesium Hydroxide- Mg(OH)2

-Base is strong enough to neutralise the pH of stomach
-Low solubility means it is not strong enough to damage body.

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19
Q

What group 2 hydroxide neutralises soil?

A

Calcium hydroxide - Ca(OH)2

-‘slaked lime’
-strong base to neutralises pH

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20
Q

Hydroxide solubility increases, sulfate solubility…

A

Decreases

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21
Q

What is Barium sulfate used for and why?

A

(Barium Meal)

Consumed before an X-ray as it insoluble but dense.

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22
Q

What is Barium Chloride used for?

A

To test for sulfate ions.

-When acid is added to removes carbonate, forms a white precipitate.

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23
Q

Are group 7 Halogens reactive?

A

Very

24
Q

Halogen + metal =?

A

Salts

25
Q

What is a halide?

A

When halogens gain an electron and become ions e.g chloride, fluoride

26
Q

What is fluorine at room temp?

A

Pale yellow gas

27
Q

What is chlorine at room temp?

A

Green gas

28
Q

What is bromine at room temp?

A

Red/brown liquid

29
Q

What is iodine at room temp?

A

Black or dark grey solid

30
Q

What is astatine at room temp?

A

Black or dark grey solid

31
Q

All halogens form ______ molecules

A

Diatomic

32
Q

What is the trend in electronegativity of group 7 and why?

A

Decreases down

-More full shells, increases shielding, increases atomic radius, electron pair is further away from nucleus
-This outweighs increase in nuclear charge.

33
Q

What is the trend in boiling point of group 7?

A

Increases down

-More mass, electrons, size, surface area
-Stronger VDW forces
-More energy needed to overcome forces

34
Q

Describe the oxidising ability of halogens

A

Decreases down, fluorine being the best

-tend to gain an electron (halides)
-oxidising agents in redox, become 1- ions.
-in a displacement reaction, fluorine will always displace another halogen.

35
Q

Describe the reducing ability of Halides

A

Increases down the group, iodide the best

36
Q

Discuss the reducing ability of NaBr with sulphuric acid

A

Acid-base reaction= HBr, a steamy gas

Redox reaction= Br2, a brown steamy gas

37
Q

Discuss the reducing ability of NaI with sulphuric acid

A

Acid-base reaction= HI, steamy fumes

Redox reaction= H2S, yellow solid or rotten eggs smell,
or I2, dark grey solid

38
Q

What would you use to identify halides?

A

Silver nitrate

39
Q

What happens to the halides when silver nitrate is added to them dissolved in water?

A

F- = no ppt (soluble)
Cl- = white ppt
Br- = cream ppt
I- = pale yellow ppt

become silver fluoride…

40
Q

If the halide has impurities, what can you react it with?

A

Dilute nitric acid

-gets rid of carbonates and forms CO2 and H2O

41
Q

What are the further tests to adding silver nitrate to halides, that help us identify?

A

Dilute ammonia:
Cl- = colourless
Br- = cream
I- = pale yellow

Concentrated ammonia:
Cl- = colourless
Br- = colourless
I- = pale yellow

42
Q

Cl2 + water =?

A

Dissociates to form Cl- ions, forming either:

HCl (hydrochloric acid)
HClO ( chloric 1 acid)

-a disproportionation reaction

43
Q

What does HClO dissociate to and how is it useful?

A

H+ and ClO-

ClO- (chlorate ion) is an oxidising agent that is toxic and will kill bacteria (used in chlorination).

44
Q

What are the pros and cons of chlorination?

A

+Kept at harmless concs
+Saved millions of lives

-Toxic
-Wasteful (only 1% of water we drink)

45
Q

Write the chemical equation for the disproportionation of chlorine and water

A

Cl2 + H2O <> HCl + HClO

<>= reversible reaction

46
Q

What happens when sunlight is a factor in the chlorine + water reaction?

A

Produces HCl + O2

There is no HClO to kill bacteria, a problem in pools

47
Q

Bleach is an oxidising agent, how is it formed?

A

Chlorine + cold, dilute sodium hydroxide

forms NaClO

48
Q

What happens to the atomic radius across period 3 and why?

A

Decreases

More protons in the nucleus, an electrostatic attraction to electrons, pulling them in, decreasing size.

49
Q

Describe the trend in First ionisation energy across period 3.

A

Increases across, due to increase in nuclear charge.

Dip between Mg and Al: electrons start to fill the p-sub shell in Al, so a small increase in shielding, less energy to remove an electron.

Dip between P and S: in group 5, each p sub unit has one electron in it but in group 6 there is 2, so spin pair repulsion occurs, already repel each other making it easy to remove.

50
Q

What is the bonding of the period 3 elements?

A

Na, Mg, Al: metallic

Si: Giant covalent lattice (metalloid)

P, S, Cl: covalent

51
Q

Describe the trend in melting points for metals of period 3

A

Melting point increases going across as the metal cations have a higher charge, so number of delocalised electrons increases, more electrostatic attraction, higher temps needed.

52
Q

Describe the covalent bonding in silicon

A

-Can bond to any number of other silicon atoms, so can make a giant covalent lattice
-A macromolecule

53
Q

What molecule does phosphorus go around as?

A

P4

54
Q

Describe the trend in melting points of the non-metals in the period 3 elements

A

Highest:

Silicon- giant covalent lattice, strong bonds
Sulphur- simple molecule, more VDW due to size
Phosphorus- less VDW
Chlorine- even less VDW
Argon- no molecules

Lowest

55
Q

What molecule does sulphur go around as?

A

S8

56
Q

What trend can we/ can not generalise to other periods?

A

Can:
-Atomic radius
-1st IE

Cannot:
-Melting points