Atom model and the Periodic Table

Who first ordered elements according to their atomic mass?

John Dalton

What was the ‘law of octaves’?

Every eighth element has repeating properties

Who discovered the ‘law of octaves’?

John Newlands

Who left gaps for undiscovered elements?

Dmitri Mendeleev

What did the spaces in the periodic table allow Mendeleev to do?

Predict the properties of undiscovered elements (e.g. eka-silicon / Gallium)

How did Mendeleev change mass order?

By switching elements who’s chemical properties did not match (e.g. Iodine and Tellerium)

Who rearranged the peiodic table to what we know today?

Henry Moseley

Why did Moseley rearrange the periodic table?

Because protons were discovered

How did Moseley rearrange the periodic table?

In atomic (proton) order

What is the electronic configuration of an atom with three full electron shells?

2, 8, 8

What do the groups on the periodic table show?

The amount of valence electrons an element in the group has

What do the periods on the periodic table show?

The amount of shells an element has

What is a valence electron?

An electron on the outer shell

What is Group 1 on the periodic table called?

Alkali metals

What is Group 2 on the periodic table called?

Alkaline earth metals

What is Group 7 on the periodic table called?

Halogens

What is Group 8 / 0 on the periodic table called?

Noble gases

What are the intermolecular force of an atom?

The forces of attraction between the negative electrons and the positive protons

Are intermolecular forces of an atom stronger in a Period 2 or Period 7 element?

Period 2

What does ‘shielding’ mean?

The blocking of the valence shell moving by the intermolecular forces between the valence electron and the nucleus

Why does reactivity increase down Group 1?

Because there are less intermolecular forces between their valence electron and their nucleus, so they lose their electron more easily

What was John Dalton’s atomic model called?

Solid sphere model

Give one feature of the solid sphere model

1. Had no subatomic particles
2. Had no charge

Name one of the four postulates of Dalton’s theory

• All elements are composed of invisible particles called atoms

• Atoms of the same element are identical

• Atoms of different elements mix and combine in whole-number ratios

• Chemical reactions occur when atoms separate, join, or rearrange

Who discovered the electron?

J.J. Thomson

What was J.J Thomson’s atomic model called?

The Plum Pudding model

Give one feature of the Plum Pudding model

• Positively charged solid sphere

• Electrons randomly buried inside

What was Ernest Rutherford’s atomic model called?

The nuclear model

Give one feature of the nuclear model

• Positively charged nucleus

• Negatively charged electrons

• Electrons move about randomly

How did alkali metals get their name?

Group 1 metals react easily with water to form an alkaline solution

Give the symbol equation for Lithium reacting with water.

Li + H20 →LiHO + H

Give the word equation for Potassium reacting with water.

Potassium + water→ Potassium hydroxide + hydrogen

How do alkali metals react with oxygen?

Alkali metal + oxygen → alkaline oxide

How do alkali metals react with chlorine?

Alkali metal + chlorine → alkaline chloride

How many valence electrons do alkali metals have?

1

Name the first 5 alkali metals.

Li (lithium), Na (sodium), K (potassium), Rb (rubidium)

Why are the alkali metals so reactive?

They only need to displace one electron

Why are alkali metals more reactive down the group?

Because there is more distance between the nucleus and valence electron, meaning there are less forces between them, making it easier for them to lose their valence electron

Do boiling / melting points decrease up or down the group?

Down the group

In general, do alkali metals have high or low melting/boiling points?

Low melting points

Does density increase or decrease down the group?

Decrease

In general, do alkali metals have high or low densities?

Low density

Give a property of alkali metals.

• Good thermal conductors

• Good electrical conductors

• Ductile

• Malleable

What group are Halogens?

Group 7

How many valence electrons do Halogens have?

7

Are Halogens more reactive up or down the group?

Up the group

Why are Halogens more reactive up the group?

Because the intermolecular forces are stronger, so it gains electrons more easily

Name the first four Halogens.

Fl (fluorine), Cl (chlorine), Br (bromine), I (iodine)

Will Fl2 + 2NaCl happen?

Yes, Fl2 + 2NaCl → 2NaFl + Cl2

What is a displacement reaction?

When a more reactive substance take the place of a less reactive substance in a compound

Name the apparatus used for filtration.

Beaker, funnel, filter paper, conical flask

What does filtration separate?

Insoluble solutes in a mixture