so chemistry is not my forte as such but as few of its topics are in my syllabus I’ll b briefing this small topics for now..
Structure of Matter:
– Matter is defined as “that which occupies space” and comprises a great number of different materials.
– Built up from smaller substances(elements) which cannot be split into smaller materials.
– All other substances are compounds formed by union of two or more elements.
Element: “Basic substance which cannot be split into simpler substances.”
Compound: “Formed by union of two or more elements.”
Molecule: “Smallest partive of any substance, element or compound, that can exist alone.”
Atom: “Smallest particle of element that can take part in chemical reaction.”
Structure of Atom:
1- All atoms are built up from three particles:
i) Proton: particle bearing positive charge of very small mass(1/2,000,000,000,000 of an inch)
ii) Neutron: Same mass as proton but with neutral charge.
iii) Electron:Still smaller with negative charge.
2- The number of protons in an atom is important as it determines the element of which it is in an atom.
eg.: hydrogen- 1,helium- 2,lithium- 3,beryllium- 4 and so on.
3- In small atoms, often the number of neutrons is equal to number of protons. In large atoms, the size in neutrons is more than that of protons.
4- The number of electrons in atom are generally equal hence making it electrically neutral.
Its arrangement is that like a solar systems (planets revolving around the sun) where the central nucleus acts as the sun and the revolving electrons as the planets.
Protons and neutons are held tightly together by strong cohesive force to form central nucleus of atom.
Clayton’s electrotherapy 4th edition