Elements are chemically the simplest substances and hence cannot be broken down using chemical reactions. Each element has a name. The name of an element is abbreviated by a one or two-letter symbol, called chemical symbol. The first letter of the chemical symbol is a capital letter, while the second letter (if there is one) is a lowercase letter. Some elements have symbols that derive from earlier, mostly latin names, so the symbols may not contain any letters from English name.

In any formula of a chemical, always symbols are used to identify the element present in that chemical. Most cases, number of unit of a particular element (atoms) are written as subscript.

For example, most people take caffeine in every day. Caffeine has chemical formula: C₈H₁₀N₄O₉and the structure of caffeine looks like the structure below:

It means that a caffeine molecule is made of four different elements, carbon, hydrogen, oxygen and nitrogen. There are 14 carbon atoms, 18 nitrogen atoms, 4 nitrogen atoms and and 9 oxygen atoms are present in one unit of caffeine.

The definition of atoms and molecules will be discussed in later section of this chapter.

Have fun listening to this song!
https://www.youtube.com/watch?v=rz4Dd1I_fX0

To know the names of each element please visit: https://www.flickr.com/photos/mrspugliano/5351057718/in/photostream/

Question:

Identify the elements in each chemical formula and tell how many atoms of each are present?
a) K₂Cr₂O₇,
b) C₅H₈NNaO₄ (MSG, flavor enhancer)
c) C₁₀H₁₆N₂O₃S(Vitamin B7)

Ans: a) Potassium, Chromium, Oxygen

Potassium-2, Chromium-2, Oxygen-7

b) Carbon, Hydrogen, Nitrogen, Sodium, Oxygen

Carbon-5, Hydrogen-8, Nitrogen-1, Sodium-1, Oxygen-4.

c) Carbon, Hydrogen, Nitrogen, Oxygen, Sulfur

Carbon-10, Hydrogen-16, Nitrogen-2, Oxygen-3, Sulfur-1

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