11
Matter can neither be created nor destroyed. Hence, the number of each type of
atom on both sides of a chemical reaction should be the same. Balancing chemical
reactions is the process of making certain the conservation of matter.
As per IUPAC (2015b), the “oxidation state” of an atom in a molecule is the
number of valence electrons it has gained or lost.
Metals and non-metals play important roles in human health and so do acids as
well as bases. The distinction between metals and non-metals is by no means clear
(Cracolice and Peters 2011), and some elements that lack a preponderance of either
non-metallic or metallic properties are grouped as metalloids.
Metals are diverse substances, with different properties and characteristics.
Metals in the environment vary and distribution of metals is governed by the properties of the metal and influences of environmental factors. Out of the 92 naturally
occurring elements, following metals and metalloids (intermediate between metals
and non-metals) are potentially toxic to humans:
1. Aluminum.
2. Antimony.
3. Arsenic.
4. Barium.
5. Beryllium.
6. Bismuth.
7. Boron.
8. Cadmium.
9. Cesium.
10. Chromium.
11. Cobalt.
12. Copper.
13. Gold.
14. Lead.
15. Lithium.
16. Manganese.
17. Mercury.
18. Molybdenum.
19. Nickel.
20. Palladium.
21. Platinum.
22. Selenium.
23. Silver.
24. Strontium.
25. Tellurium.
26. Tin.
27. Titanium.
28. Tungsten.
29. Vanadium.
1.2 General Chemistry
Matter can neither be created nor destroyed. Hence, the number of each type of
atom on both sides of a chemical reaction should be the same. Balancing chemical
reactions is the process of making certain the conservation of matter.
As per IUPAC (2015b), the “oxidation state” of an atom in a molecule is the
number of valence electrons it has gained or lost.
Metals and non-metals play important roles in human health and so do acids as
well as bases. The distinction between metals and non-metals is by no means clear
(Cracolice and Peters 2011), and some elements that lack a preponderance of either
non-metallic or metallic properties are grouped as metalloids.
Metals are diverse substances, with different properties and characteristics.
Metals in the environment vary and distribution of metals is governed by the properties of the metal and influences of environmental factors. Out of the 92 naturally
occurring elements, following metals and metalloids (intermediate between metals
and non-metals) are potentially toxic to humans:
1. Aluminum.
2. Antimony.
3. Arsenic.
4. Barium.
5. Beryllium.
6. Bismuth.
7. Boron.
8. Cadmium.
9. Cesium.
10. Chromium.
11. Cobalt.
12. Copper.
13. Gold.
14. Lead.
15. Lithium.
16. Manganese.
17. Mercury.
18. Molybdenum.
19. Nickel.
20. Palladium.
21. Platinum.
22. Selenium.
23. Silver.
24. Strontium.
25. Tellurium.
26. Tin.
27. Titanium.
28. Tungsten.
29. Vanadium.
1.2 General Chemistry