Classwork Series and Exercises {Chemistry- SS1}: Elements and Symbols

Elements and Symbols

The atoms are particles of elements and are represented by chemical symbols. A chemical symbol is a sign and it is made up of a letter or two letters to represent the atom of the element. Chemical symbols of atom of elements are derived from the names of the elements.

The following rules are used for deriving symbols:

• The first letter of the name is taken and this is written as a capital letter e.g. C for Carbon.
• The first and the second letters of the name is taken and first is written in capital letter while the second is in small letter e.g. Ca for Calcium, Al for Aluminium.
• Some first and the third letters of the name is taken and the first is written in capital letter while the third is in small letter e.g. Mg for Magnesium
• Some elements have Latin names, the symbols are derived from the Latin names e.g. The symbol for copper is Cu from Latin name is cuprum

A list of some elements is shown below:

Element	Symbol	Atomic Number	Atomic Mass	Number of Protons	Number of Neutrons
Hydrogen	H	1	1	1	0
Helium	He	2	4	2	2
Lithium	Li	3	7	3	4
Beryllium	Be	4	9	4	9
Boron	B	5	11	5	6
Carbon	C	6	12	6	6
Nitrogen	N	7	14	7	7
Oxygen	O	8	16	8	8
Fluorine	F	9	18	9	9
Neon	Ne	10	20	10	20
Sodium	Na	11	23	11	12
Magnesium	Mg	12	24	12	12
Aluminum	Al	13	27	13	14
Silicon	Si	14	28	14	14
Phosphorous	P	15	31	15	16
Sulphur	S	16	32	16	16
Chlorine	Cl	17	35	17	16
Argon	Ar	18	40	18	22
Potassium	K	19	39	19	20
Calcium	Ca	20	40	20	20

Iron                     Fe                          26               56                      26              30

Copper                Cu                          29             63.5                     29              34.5

Zinc                    Zn                          30             65.5                     30              35.5

VALENCY

Valency is defined as the combining power of any element. Valence describes how easily an atom or radical can combine with other chemical species. This is determined based on the number of electrons that would be added, lost or share if it reacts with other atoms. Valence is denoted using a positive or negative integer used to represent this binding capacity. For example, common valences of copper are 1 and 2.

Table of Element Valences

Number	Element	Valency
1	Hydrogen	1
2	Helium	0
3	Lithium	1
4	Beryllium	2
5	Boron	3
6	Carbon	2 and 4
7	Nitrogen	3 and 5
8	Oxygen	2
9	Fluorine	1
10	Neon	0
11	Sodium	1
12	Magnesium	2
13	Aluminum	3
14	Silicon	4
15	Phosphorus	3 and 5
16	Sulphur	2, 4 and 6
17	Chlorine	1
18	Argon	0
19	Potassium	1
20	Calcium	2
21	Scandium	3
22	Titanium	2 and 4
23	Vanadium	3 and 5
24	Chromium	2, 3 and 6
25	Manganese	2, 4 and 7
26	Iron	2 and 3
27	Cobalt	2 and  3
28	Nickel	2 and 4
29	Copper	1 and 2
30	Zinc	2

Example 1: 2 atoms of hydrogen will combine with 1 atom of oxygen to form water.

Therefore, the valency of oxygen is 2.

Example 2: 1 atom of zinc will displace 2 atoms of hydrogen.

Therefore, the valency of zinc is 2.

EXERCISES

Lets see how much you’ve learnt, attach the following answers to the comment below

1. These are basic particles from which matter could be made except (a) salt (b) atoms (c) ions (d) molecules
2. Which of these is the same in isotopes of an element? (a) mass number (b) number of neutrons (c) atomic number (d) number of neutron and proton
3. What are the correct symbols of Aluminium, Silver and Mercury? (a) Na, Si & Mc (b) Al, Ag & Hg (c) Al, S & M (d) Mg, Al & H
4. All these exhibit isotopy except (a) carbon (b) Hydrogen (c) Oxygen (d) Chlorine
5. ________ describes how easily an atom or radical can combine with other chemical species. (a) symbol (b) valence (c) orbital (d) electronic configuration

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