Chemistry of You

99% of the mass of the human body is made up of only six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Every organic molecule contains carbon. Since 65-90% of each body cell consists of water (by weight), it isn't surprising that oxygen and hydrogen are major components of the body.

Source : chemistry.about.com/od/periodictableelements/ig/Elements-in-the-Human-Body/

Gold Alloys

When you buy gold jewelry, it isn't pure gold. Your gold is really an alloy, or mixture of metals. The purity or fineness of gold in the jewelry is indicated by its karat number. 24 karat (24K or 24 kt) gold is as pure as gold for jewelry gets. 24K gold is also called fine gold and it is greater than 99.7% pure gold. Proof gold is even finer, with over 99.95% purity, but it is only used for standardization purposes and is not available for jewelry.

So, what are the metals that are alloyed with gold? Gold will form alloys with most metals, but for jewelry, the most common alloying metals are silver, copper, and zinc. However, other metals may be added, especially to make colored gold.

Source : chemistry.about.com/od/jewelrychemistry/a/goldalloys.htm

Mnemonic - The Reactivity / Electrochemical Series

The suggestable mnemonic for the Reactivity Series is :
Please Send Camels, Monkeys And CARBON Zebras with HYDROGEN In Tom's Large Containers of Solid Gold


Please (Potassium)
Send (Sodium)
Camels (Calcium)
Monkeys (Magnesium)
And (Aluminium)
CARBON
Zebras with (Zinc)
HYDROGEN
In (Iron)
Tom's (Tin)
Large (Lead)
Containers 0f (Copper)
Solid (Silver)
Gold

Whereas, for the Electrochemical Series, the suggestable mnemonic is :
Please Send Camels, Monkeys And Zebras In Tom's Large HYDROGEN Containers of Solid Gold

The reactivity series and the electrochemical series are quite similar except for the addition of carbon element and different position of hydrogen element in the reactivity series. Therefore, it is advisable for you to just memorised carbon and hydrogen at heart.