# Unit 1: Chemistry

- Matter - has mass, takes up space.
    - fundamental unit -> ATOMS

## Atoms
- Atoms are the smallest unit of an element that still retains its properties
- Atoms are made of subatomic particles
- Relative Charge: compared to something. 
- AMU = atomic mass units
- models allow people to make accurate preictions about the behaviour of matter
- atmoic notation $`_{19}K`$
- an isotope is an atom (or atoms) of an element with a unique # of neutrons

|Name     |Symbol|Relative mass (amu)|Location|Relative Charge|
|:--------|:-----|:------------------|:-------|:--------------|
|Protons  |$`p^+`$|       $`1`$          |nucleus | $`+1`$        |
|Neutrons |$`n^0`$|     $`1`$            |nucleus | $`0`$         |
|Electrons|$`e^-`$|$`~\dfrac{1}{2000}`$|in orbit around nucleus (shell, energy level)|$`-1`$|

## IUPAC
|Letter|Definition|
|:-----|:---------|
|I|International|
|U|Union|
|P|Pure and|
|A|Applied|
|C|Chemistry|

- Involved in studying, varifying information (eg the periodic table -> Describes the elements -> pure susbtances made of only one kind of atom),and publishing.

## Trends on the Periodic Table
- Same energy level in each period
- Same number of valence electrons in each group
- Across a row/period $`\rightarrow`$ more $`p^+`$ in nucleus $`\rightarrow`$ greater attraction to $`e^-`$
- s 

## Metals
- They tend to lose electrons
- They are shiny, ductile, malleable, conductive
- They have a weak/loose hold on electrons

## Non-Metals
- They are dull, bad conductors - insulators
- Tend to gain electrons
- The have a strong hold on electrons