When I was at school, ooh just a few years back ahem... I had a chemistry test which involved knowing the first 20 of the elements of the periodic table off by heart. Luckily my brother had taught me the following mnemonic.

Once you learn it you can never forget it, well at least I can't

So here it is - The easier method of memorizing the first twenty elements of the periodic table:

For all the Him & Hers -
Little Betty Bright Child, Nurses Our Friends Neatly. Nasty Magy Always Sings Pop Songs Clearly Around Kirsty Carol

I'm afarid you're just gonna have to remember the first two elements the old fashioned way, or the lame way I've stated above...

It all corresponds to the following -
H : Hydrogen
He : Helium
Li : Lithium
Be : Beryllium
B : Boron
C : Carbon
N : Nitrogen
O : Oxygen
F : Fluorine
Ne : Neon
Na : Sodium
Mg : Magnesium
Al : Aluminium / Aluminum
Si : Silicon
P : Phosphorous
S : Sulphur
Cl : Chlorine
Ar : Argon
K : Potassium
Ca : Calcium