BASICS OF CHEMISTRY

1. ATOM: An atom is the smallest particle of an element which can take part in chemical reaction e.g.

2. ELEMENTS: An element is a substance which cannot be splitted into fractions by an ordinary chemical means and can be represented with symbols e.g. Aluminum (Al), Hydrogen (H), Oxygen (O) etc.

3. COMPOUND: This is the combination of two or more element that are chemically combined together e.g. C_(s) + O_(g) → CO_2(g) {i.e ELEMENTS +ELEMENTS ----> COMPOUND}

4. MOLECULE: This is the smallest part of a chemical compound, that can take part in a chemical reaction. A molecule may be of a compound (e.g. H₂O CO₂) or of an element e.g. O₂, Cl_2, H_2, F₂,  .

5. MIXTURE: These are substances that contain two or more constituents which may be an element or a compound or both in samples of a given mixture and can be separated by physical means e.g. Crude oil, blood, Urine, milk etc Mixture may be of similar phases [HOMOGENOUS e.g water and salt ]or different phases [HETEROGENOUS e.g water and lubricating oil.]

6. ION: An ion is any atom or group of atom possessing electrical charges.

CATION: Positively charged ion e.g. K⁺_, Na⁺_, Ca²⁺_, Al ³⁺.

ANION: Negatively charged ion e.g. C l^- , O^2-,

7. VALENCY: This is the combining power of an element and can be referred to as the oxidation number. valencies are usually whole numbers that are positive in metals and negative in non-metals. Valency  enable us to construct the formula of compounds from component elements. An element may be Monovalent or Univalent, Divalent, Trivalent, Tetravalent or Quadrivalent. The periodic table gives great insight into the valency of each element as element belonging to the same group possess similar valency.

8. RADICAL: These are charged group of atom that behave as unit and do not exist separately outside a compound. E.g.  SO4^2-,   NO₃^2-. CO₃^2-. Cr₂O₇^2-.

9. PROTON: An atomic sub-particle usually positive and located in the atomic nuclei. Proton  are whole numbers and always increase by one (1). Besides, it also determines the atomic number of an element [proton is hydrogen ion]

10. NEUTRON: An atomic sub-particle usually neutral and located in the atomic nuclei. The combination of proton and neutron present in nucleus of an atom result in mass number (i.e P + N = A). However, instability of neutron in nucleus of an atom results in Isotopy. Neutron is not present in hydrogen atom (proton), but present in its isotope Deuterium and Tritium.

11. ELECTRON: An atomic sub-particle usually negative and located on orbit known as shells. Electron revolves round the centrally placed nucleus in an orbital manner. In every atom, the number of proton (i.e P or Z) is always equal to number of electron (i.e P = E) except during chemical combination when a Duplet or Octet arrangement seems to represent stability. They are also responsible for beta emission during radioactivity(.

12. MASS NUMBER: This is the sum total of proton and neutron present in the atomic nucleus of an element and it's usually represented with letter. ["A" (mass number) , Z (atomic number ) X symbol]     Mass number = A, A = P + N and N = A - P.

13. ATOMIC NUMBER: This is the number of proton present in the atomic nucleus of an element. Atomic number () is denoted by letter "Z" and increases by one (1) when the element are arranged in order of ascending relative atomic mass (Z=P). Atomic number =Z Hence Z = P, and P = E (in neutral atom). Atomic number are usually whole numbers and are usually the identity and most unique property of an element.

14. ISOTOPY: This is the existence of atom having the same atomic number (Z) but different mass number (A) and atom exhibiting these are said to be isotope. Isotopy is usually influenced by difference in number of neutron . Proton  () Deuterium() and Tritium().

15. ALLOTROPY: This is the ability of elements to exists in various forms in the same physical state. Elements that exhibit allotropy includes; Carbon, Sulphur, Silicon, Phosphorus.

16. ELECTROYSIS: This is the production of chemical reaction by passing an electric current through an electrolyte. It is also known as the process of passing current through solutions of electrolyte resulting in chemical decomposition at the electrode

17. ELECTROLYTE: These are the solutions of acids, bases and salts or substances in molten states that can conduct electricity. There are THREE types of electrolyte and these areI. STRONG ELECTOLYTE: Dissociate completely e.g HCl, H₂SO_4, NaOH, Ca[OH]₂

    II. WEAK ELECTROLYTE : Does not dissociate completely e.g CH₃COOH, H₂CO₃

    III. NON-ELECTROLYTE :Cannot conduct electricity even when molten e.g Sugar Urea

19. ELECTRODE: are the poles of the cell and there are two types of electrode

Anode and cathode

IN ELECTROLYTIC CELLS the ANODE is positive electrode and oxidation occurs here while the CATHODE  is negative electrode where reduction  takes place.

IN ELECTROCHEMICAL CELLS the CATHODE  is positive electrode and reduction occurs here while the ANODE is negative electrode and oxidation takes place.

ELECTROLYTIC CELLS	ELECTROCHEMICAL CELLS
Anode is positive electrode	Cathode  is positive electrode
Oxidation occurs at the anode	Oxidation occurs at the anode
Cathode  is negative electrode	Anode is negative electrode
Reduction occurs at the cathode	Reduction occurs at the cathode

20. OXIDATION AND REDUCTION:

PROCESSES	OXIDATION	REDUCTION
WITH OXGYEN	ADDITION	REMOVAL
WITH HYROGEN	REMOVAL	ADDITION
OXIDATION NUMBER	INCREASE	DECREASE
ELECTRON TRANSFER	LOSS OF ELECTRON	GAIN OF ELECTRON
WITH ELECTRONEGATIVE ELEMENT	PRESENCE	ABSENCE

OXIDIZING AND REDUCING AGENTS:

OXIDIZING AGENT	REDUCING AGENT
Gains electron (acceptor)	Loses electron (donor)
Reduced during chemical reaction	Oxidized during chemical reaction
Their oxidation states reduces	Their oxidation states increases
Possess high electronegativity	Possess low electronegativity
Possess high ionization energy	Possess low ionization energy
Possess low atomic radius	Possess high atomic radius
E.g. Halogens ,KMnO4,NO3, K2Cr2O7, O2 , O3	E.g. H2S,

PRACTICE QUESTIONS

1.  In a tabular form , classify the following substances into Element, Atom, Compound, Mixture, Anion, Cation,  Isotope Allotrope Electrodes and Electrolyte, [Carbon rod, H₂SO_4, NO₃^2-.Crude oil ,Water, Sulphur, K⁺_, Urine, Diamond,

Platinum rod, Ozone, Sugar,  O^2- , 

2.  COPY AND COMPLETE THE TABLE BELOW

S/N	ELEMENTS	A	Z	P	E	N	VALENCE	GROUP
1					20
2							+1
3			16
4								7

3. A,Z,P,E and N represent_______? AND DEFINE A,Z,P,E and N

4. Define oxidation in terms of electron transfer.

5. COPY AND COMPLETE THE TABLE BELOW

S/N	ATOMIC NO	ELECTRONIC CONFIGUR	GROUP	PERIODS	VALENCY	CHLORIDES	OXIDES
1	6
2		1S22S22P63S23P1
3			2	3
4			5	2
5		1S22S22P63S23P8