C2- The periodic table 🧪

Question 1

What do all the elements in a group have and why?

Hint: chemical

Answer 1

• All of the elements in a group, have similar chemical properties. This means the react in a similar way.
• This is because all the elements in a group, have the same number of electrons in their outer energy shell

Question 2

How did Newlands’ arrange elements?

Answer 2

• Newlands arranged elements, in order of their increasing atomic weight.
• And he saw every eight element, reacts in a similar way. [in a law of octaves]

Question 3

What was the problem of how Newlands’ arranged elements?

Hint: different

Answer 3

• Because he ordered elements, by their atomic weight, sometimes elements were grouped together, even if they had different properties.
• Therefore his ‘law of octaves’ wasn’t taken seriously by other scientists.

Question 4

How did Mendeleev develop the first modern periodic table ?

Hint: so they fitted the pattern

Answer 4

• Mendeleev arranged all the elements in order of their increasing atomic weight; he switched the order of specific elements if he needed to- so they fitted the pattern of other elements, in the same group.
• He also left gaps in the periodic table where he thought some were missing- as he realised some elements hadn’t been discovered.

Question 5

What is the difference between the modern periodic table, 🆚 Mendeleev’s periodic table ?

Hint: number, protons

Answer 5

• In the modern periodic table, the elements are arranged in order of their atomic number
• ; when Mendeleev developed his periodic table, protons were undiscovered- [therefore, he ordered the elements by atomic weight]
• the modern periodic table has group 0 (the nobles gases); these weren’t fully discovered when Mendeleev has published his table.

Question 6

What is a promblem of ordering elements based on their atomic weight?

Hints: presence of isotopes

Answer 6

• elements can appear in the wrong order, due to the presence of isotopes

Question 7

What are group 0 called?

Answer 7

• group 0 are called the noble gases

Question 7

What are group 0 called?

Answer 7

• group 0 are called the noble gases

Question 8

Why are the noble gases unreactive ?

Answer 8

• the noble gases are unreactive because all the nobles gases have a full outer energy level/ a full outer shell.

Question 9

Describe the boiling points of the noble gases

Answer 9

• the boiling points of the noble gases increase, as the relative atomic masses increase [going down the group].

Question 10

Explain why the boiling points of the noble gases change.

Hint: number of electrons

Answer 10

• The boiling points of the noble gases increases as you go down the group.
• This is because of an increase in the number of electrons in each atom, leading to greater intermolecular forces between them, which need to be overcome

Question 11

Where are metals found in the periodic table?

Answer 11

• In a periodic table, metals are found in the left and centre of the periodic table.

Question 12

What happens when metals reacts?

Hint: electrons

Answer 12

• when metals react, they lose electrons to achieve a full outer shell/outer energy level.
• This then gives them the same electronic structure as group 0: the noble gases.

Question 13

What do metals always form, when they lose electrons?

Answer 13

• metals always form positive ions, when they lose electrons.

Question 14

What are group 1 called?

Answer 14

• group one are called the alkali metals.

Question 15

What is a specific feature about group one metals?

Hint: one

Answer 15

• all group 1 metals have one electron in their outer energy level/outer shell

Question 16

How do group one metals react with oxygen?

Answer 16

• all group one metals react rapidly with oxygen, reacting more rapidly as you move down the group.

Question 17

How do group one metals react with chlorine?

Answer 17

• all group one metals react rapidly with chorine.

Question 18

How do group one metals react with water?

Answer 18

• group one metals react vigorously with water.
• For example, lithium has a fast reaction, sodium has a very fast reaction and potassium has an extremely fast reaction water.

Question 19

Why do elements get more reactive as you move down group one ?

Hint: easier to lose

Answer 19

• because the attraction bewteen the nucleus and outer electron decreases, meaning the outer electron is easier to lose
• This is because there’s a greater distance, between the positive nucleus and the negative outer electron.
• Moreover, the outer electron is shielded from the nucleus, by the internal energy levels.

Question 20

What are the trends of group 1? [3]

Answer 20

• increasing in reactivity, as you move down the group.
• lower boiling points and melting points, as you go down the group
• and a higher relative atomic mass, as you go down the group

Question 21

Why did scientists accept Mendeleevs periodic table ?

Answer 21

• Mendeleev was able to predict properties of undiscovered elements, based on other elements that are in the same group.
• ; scientists accepted that his table was correct, because years later after the elements were discovered, their properties matched his predictions