C2: The Periodic Table

Question 1

What was the John Newland’s version of the periodic table?

Answer 1

1864- Noticed periodicity based on elemental mass and sorted elements by mass
- Law of Octaves- Every 8th (known) element was similar
- Not similar properties in each group
- Compounds
- 2 in same box
- Hydrogen not by itself

Question 2

What was Dmitri Mendeleev’s version of the periodic table?

Answer 2

Dmitri Mendellev (1869) “Father of the periodic table”:
- Also arranged elements by mass (atomic weight) and property but included empty spaces for irregular jumps in mass
- These accounted for undiscovered elements of which he successfully predicted
- Groups
Hydrogen by itself but in a shared group
- Still multiple elements in a single box

Question 3

Why was the periodic tabke so important?

Answer 3

Now each chemical element had its number and fixed position in the table, and from this it became possible to predict its behaviour: how it would react with other elements, what kind of compounds it would form, and what sort of physical properties it would have.

Question 4

Why are the noble gasses unreactive?

Answer 4

Elements react to gain a full outer shell through losing/ gaining electrons. However, noble gasses already have full outer shell of valence electrons so chemical reactions are uneccessary, resulting in them being extremelly unreactive.

Question 5

What changes as the group change?

Answer 5

Number of electrons

Question 6

What changes as you go diwn the periods?

Answer 6

Number of shells

Question 7

How is the electronic structure of non-metals and metals different?

Answer 7

Atoms of metal elements give away electrons in their reactions to form positive ions. The ions formed have a full outer electron shell, so are very stable. Atoms of reactive non-metal elements gain electrons in some of their reactions to form negative ions.

Question 8

How does an atoms electronic strucutre affect its reactivity

Answer 8

Elements with a nearly full or nearly empty outer shell are often highly reactive, as they can easily gain or lose electrons to achieve a full outer shell.

Question 9

What is the equation of Li (group 1) reactions with water?

Answer 9

Li + H2O = LiOH + H2
Balanced:
2Li + 2H2O = 2LiOH + H2

Question 10

What is the equation of Na (group 1) reactions with water?

Answer 10

Na + H2O = NaOH + H2
Balanced:
2Na + 2H2O = 2NaOH + H2

Question 11

What happens when a group 1 metal reacts with water?

Answer 11

Hydrogen gas is given off and the metal hydroxide is produced

Question 12

What are group 1 elements called?

Answer 12

Alkali metals

Question 13

What are group 7 elements called?

Answer 13

Halogens

Question 14

What is the equation for K (group 1) reaction with water?

Answer 14

K+ H20 = KOH + H2
Balanced:
2K + 2H2O = 2KOH + H2

Question 15

Why do the first 3 group 1 elements float pn water when rescting?

Answer 15

lithium, sodium and potassium are less dense than water so they float on the surface of the water. the metals move about the surface of the water and fizz as hydrogen gas is produced. they will all release heat as they react as the reactions are exothermic and they will eventually disappear.

Question 16

Why do group 1 elements gain a 1+ charge when reacting with non-metals?

Answer 16

Group 1 elements have 1 valence shell. 1 negatively charged electron is lost to gain a full outer shell. ‘Element’ - -1 = ‘Element’ 1+ charge

Question 17

How are group 1 metals stored?

Answer 17

Stored under mineral oil to prevent from oxidising with watee vapour/ oxygen. This prevents the metals from reacting and causing potential hazards (eg: When potassium reacts with water, it creates a flame)

Question 18

Give the displacement reactions of group 7 elements

Answer 18

KCl + Cl2 = No reaction
KBr + Cl2 = KCl Br2
KI + Cl2 = KCl + I2

Question 19

Why do some group 7 elements have no displacement reaction with eg: KBr

Answer 19

Because the element that displaces Br must be more reactive.

Question 20

What is the trend in reactivity of group 1 elements?

Answer 20

As you go down the group, reactivity increases. This is because shell sheilding increases, resulting in increased atomic radiui. This reduces the electrostatic attraction between the positive nucleus and negatively charges valence electrons. This makes it easier to lose elctrons when reacting to gain a full outer shell.

Question 21

What is the trend in reactivity as you go down the group 7 elements?

Answer 21

As you go down the group, reactivity decreases. This is because shell sheilding increases, resulting in increased atomic radiui. This reduces the electrostatic attraction between the positive nucleus and negatively charges valence electrons. This makes it harder to gain elctrons when reacting to gain a full outer shell.

Question 22

What are the properties of group 1 elements?

Answer 22

Alkali metals are soft, highly reactive with relatively low melting- boiling points. Alkali metals have large atomic radii between neighboring atoms of group 1 and show a weaker force of attraction due to which they are generally soft and thus have a low melting point. All group 1 elements have low densities.

Question 23

What are the main properties of group 7 halogens?

Answer 23

As you go down the halogens, from fluorine to astatine, the elements become darker in colour and have a higher boiling point. Boiling point increases as you go down the group because the molecules increase in size, and intermolecular forces become stronger so more energy is required to overcome the intermolecular forces. Very reactive as only 1 electron is needed to gain a full outer shell

Question 24

What are typical physical properties of transition metals and their compounds?

Answer 24

• they are good conductors of heat and electricity.
• they can be hammered or bent into shape easily.
• they have high melting points. (but mercury is a liquid at room temperature)
• they are usually hard and tough.
• they have high densities.
• They form coloured compounds
• Act as catalysts.

Question 25

What are typical chemical properties of transition metals and their compounds?

Answer 25

• they are less reactive than alkali metals such as sodium
• they form coloured ions of different charges
• some are very unreactive (silver and gold)
• many are used as catalysts

Question 26

How do the properties of Group 1 metals compare with transition metals.

Answer 26

high melting point (group 1 metals have low melting points) hard (group 1 metals are soft) high density (group 1 metals have lower densities)

Question 27

What is the use of a transition metal or its compound in terms of its chemical properties?

Answer 27

Transition metals make good catalysts. In addition, they have important magnetic properties: many transition metals are paramagnetic or ferromagnetic. They are also unreactive with oxygen and water so can be used for structures due to less rust

Question 28

Why is mercury not a typical transition metal?

Answer 28

It has an extremelly low melting point- A liquid at room temperature. The binding energy of outer electrons (towards nucleus) is highest and no electron is available to participate in metallic bond formation. Therefore, mercury does not have a specific crystal structure and is the only metal which is liquid at room temperature with a melting point of -38 degree Celsius.