The Periodic Table

Question 1

How are elements ordered in the modern periodic table?

Answer 1

By their atomic/proton number.

Question 2

What are periods? What do elements in each period have in common? (2)

Answer 2

Horizontal rows in the periodic table; elements in each row have the same number of shells.

Question 3

What are groups? What do elements in each group have in common? (2)

Answer 3

Vertical columns in the periodic table; elements are grouped by the same number of electrons in their outermost shell.

Question 4

What did Doberoëiner notice about the periodic table?

[include example]

Answer 4

Elements with similar chemical properties often occurred in three’s (triads).

e.g, lithium, sodium, potassium all are heavily reactive in water.

Question 5

What did Doberoëiner’s discovery lead scientists to believe?

Answer 5

That the elements could possibly be arranged into a logical order

Question 6

How did Newland order the elements?

Answer 6

He ordered them in increasing atomic weight, where every 8^th element had similar properties and reacted similarly.

Question 7

Why was Newland’s ‘octaves’ not taken seriously by other scientists?

Answer 7

When sticking to the exact order of atomic weight, some elements were grouped together despite having complete different properties.

Question 8

How did Mendeleev order elements? What else did he do? What is the difference between this and the modern periodic table? (3)

Answer 8

1. He ordered them in increasing relative atomic mass as protons not been discovered yet.
2. He switched the order of certain elements so they fitted patterns of properties of other elements in same group.
3. He left gaps for undiscovered elements (group 0 not been discovered) and predicted their properties using other elements - was correct.

Question 9

What is group 0 called?

Answer 9

Noble gases.

Question 10

What is the reactivity of noble gases? Why? (2)

Answer 10

They are unreactive; their atoms have a full outer shell of electrons, making them stable.

Question 11

Do noble gases form molecules? Why? (2)

Answer 11

They do not form molecules; they already have a full outermost shell, which, makes them avoid other atoms because they are totally neutral.

Question 12

What is the trend in group 0? Why? (2)

Answer 12

The boiling point increases as the relative atomic mass increases (ie. going down the group); there are stronger intermolecular attractions between electrons that need to be overcome.

Question 13

What are the majority of elements?

Answer 13

Metals.

Question 14

Where are metals and non-metals found on the periodic table?

Answer 14

• Metals: to the left side and towards the bottom of the Periodic Table.
• Non-metals: to the right side and towards the top of the Periodic Table.

Question 15

What ions do metals form?

Answer 15

Positive ions

Question 16

What is group 1 called?

Answer 16

Alkali metals.

Question 17

What is the chemical equation of alkali metals and water? What may you observe?

Answer 17

A. metal + Water —> Metal hydroxide + Hydrogen gas.
* They react vigorously with water fizzing and moving around on the surface of the water..

Question 18

What is the chemical equation of alkali metals and oxygen? What may you observe?

Answer 18

A. metals + Oxygen = White metal oxides.
* Colour of flames: Li = crimson-red, Na = yellow-orange, K = lilac.

Question 19

What is the chemical equation of alkali metals and green chlorine gas? What may you observe?

Answer 19

A. metal + Green chlorine gas = White metal chloride salts.

Question 20

What are the trends reactivity in group 1? Why is this a trend? (5)

Answer 20

The reactivity increases going down the group.⁽¹⁾ This is because the outermost electrons are further away from the nucleus as you go down the group ⁽²⁾ so the nuclear attraction weakens.⁽³⁾ There is also more shielding.⁽⁴⁾ Overall, this makes the electron easier to lose.⁽⁵⁾

Question 21

What is the reason for the reactivity trend in group 1?

Answer 21

Moving down the group, the outer electron is less attracted to the nucleus and easier to lose.
There is a greater distance between the positive nucleus and the negative outer electrons
The outer electron is shielded by the internal energy levels.