Chemistry B1

Atomic Structure and States of matter

How do you calculate Protons, Neutrons and electrons using the element

1. Protons

• The atomic number (the small whole number on the periodic table) tells you the number of protons.
  👉 Example: Carbon has atomic number 6, so it has 6 protons.

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2. Electrons

• In a neutral atom (no charge), the number of electrons = protons.
  👉 Carbon (neutral) → 6 protons, so 6 electrons.

• If it’s an ion:

  • Positive ion (e.g. Na⁺) → lost electrons, so electrons = protons – charge.

  • Negative ion (e.g. Cl⁻) → gained electrons, so electrons = protons + charge.

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3. Neutrons

• Use the mass number (the bigger number, usually above/below the symbol, often not a whole number but you round it).

• Formula:

  Neutrons=Mass Number−Protons\text{Neutrons} = \text{Mass Number} - \text{Protons}Neutrons=Mass Number−Protons

👉 Example: Carbon-12 → Mass number = 12, Protons = 6
Neutrons = 12 – 6 = 6

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✅ Quick method to remember:

• Atomic number = protons = electrons (if neutral)

• Mass number – atomic number = neutrons

Why is group 1 called the alkaline metals

Because when it reacts with water it creates an alkaline solution

Alkaline metals are stored in what and locked up because …

stored in oil to help prevent it from reacting and it is locked up to stop people stealing it and exploding the school.

When G1 metals react with Oxygen they create a what …

oxide

which element floats on water and why in g1 metals

lithium cause it has the lowest atomic mass and is the least dense.

Properties of g1 metals

• soft and malleable- increases as you go down the group

• they all have low densities - increases as you go down the group

• low melting and boiling points - decrease as you go down the group

• conduct heat and electricity

• share certain metallic properties

Word equations for alkali metals with water

Alkali metal + water → alkali metal hydroxide + hydrogen

what is the symbol formula for lithium reacting with water

2li(s) + H2O(l) → 2LiOH(aq) +H2 (g)

What is the word equation for alkali metals reacting with oxygen

Alkali metals+ oxygen → Alkali metal oxide

As you go down G1 the reactivity ?

increases

There are more electron shells therefore the radius is …

bigger

there will be less attraction between the outer shell and the

nucleus

Since the outer electron is further away from the nucleus the electron is easily lost as you go … the group

down

Group 7 is called .. because

The halogens it means salt maker which is what the halogens make when they react with water

Properties of the halogens

• Non metals - don’t conduct electricity

• Brittle and crumbly

• poisonous and smell

• They become darker and less reactive as you go down the group because they gain an electron

What colour is chlorine

Pale green

What colour is iodine

purple vapour , grey black crystal

What colour is bromine

dark red

Group nought isn’t called group 8 anymore why ?

Because the outer electron shell of heliun adds up to 2 not 8 unlike the rest of them

The colour of group 0 is

colourless

all the noble gases are reactive or not reactive

unreactive

The group number can tell you

how many electrons in the outer shell

Period tells you

how many shells it has

what is an isatope

isotopes = same element, different mass. and neutrons

what is an ion

An ion is an atom or molecule that has an electric charge because it has gained or lost electrons.

when you gain an electron you get a negative charge

because electrons have negative charges and that unbalances the equation and its an opposite for when you lose an equation

group 0 doesnt lose elctrons why

cause it already has a full outer shell

how do you form an ion

atoms form ions to get a full outer shell, either by losing or gaining electrons.

how have ideas of an atom changed over time

relative charge and mass of a proton

+1 1

relative charge and mass of a neutron

0 1

relative charge and mass of an electron

-1 1/1840

Mass =

P + N

3 states of matter

solid liquid gas