Chemistry

Ionic (Electrovalent) Bonding Noble gases like neon or argon have eight electrons in their outer shells (or two in the case of helium). These noble gas structures are thought of… Read More »STRUCTURE AND BONDING

Characteristics of periods The first period starts with hydrogen (H) and ends with helium (He). It has just two elements H (Z=1) and He (Z = 2). H has one… Read More »Periods

In this group, we have Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and Radon (Rn). The electronic configuration will show that these atoms all have a complete… Read More »THE NOBLE GASES – GROUP 0

The halogens are all in group 7 on the right of the periodic table. This group consists of elements like Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At).… Read More »The Halogens – Group 7

Going down Group 2: There are more filled energy levels between the nucleus and the outer electrons, therefore the outer electrons are more shielded from the attraction of the nucleus… Read More »Trend In Atomic Radius

As you go down the group from one element down to the next the atomic radius gets bigger due to an extra filled electron shell. The outer electron is further… Read More »REACTIVITY TREND OF ALKALI METALS

Dmitri Mendeleev is credited as being the Father of the modern periodic table. In 1869 he arranged the 50 or so known elements in order of atomic number, Z, putting… Read More »The Periodic Table

It is interesting to note that atoms of a given atomic number can have different number of neutrons. Atoms of elements having the same atomic number with different mass numbers… Read More »Isotopes

Hydrogenation/Hardening of unsaturated vegetable oils to saturated fats/margarine. When Hydrogen is passed through unsaturated compounds in presence of Nickel catalyst and about 150oC, they become saturated. Most vegetable oil are… Read More »USES OF HYDROGEN GAS

The structure of the atom When scientists started exploring matter, they realized that matter can be divided into smaller and still smaller particles. They called the smallest particle an ‘atom’.… Read More »THE STRUCTURE OF THE ATOM AND THE PERIODIC TABLE

Physical properties Hydrogen is a neutral, colourless and odourless gas. When mixed with air it has a characteristic pungent choking smell It is insoluble in water thus can be collected… Read More »PROPERTIES OF HYDROGEN GAS

Occurrence Hydrogen does not occur free in nature. It occurs as Water and in Petroleum. School laboratory Preparation Procedure Put Zinc granules in a round/flat/conical flask. Add dilute sulphuric(VI) /Hydrochloric… Read More »HYDROGEN

The higher the metal in the reactivity series the more reactive the metal with water. The following experiments show the reaction of metals with cold water and water vapour/steam. Reaction… Read More »REACTION OF METALS WITH WATER

Water pollution take place when undesirable substances are added into the water. Sources of water pollution include: Industrial chemicals being disposed into water bodies like rivers, lakes and oceans. Discharging… Read More »WATER POLLUTION

Pure water is a colourless, odourless, tasteless, neutral liquid. Pure water does not exist in nature but naturally in varying degree of purity. The main sources of water include rain,… Read More »WATER

Metals compete for combined Oxygen. A metal/element with higher affinity for oxygen removes Oxygen from a metal lower in the reactivity series/less affinity for Oxygen. When a metal/element gains/acquire Oxygen,… Read More »REACTIVITY SERIES OF METALS/ELEMENTS

The following experiments show the reaction of non-metals with Oxygen and air. Burning Carbon Procedure (a) Using a pair of tongs hold a dry piece of charcoal on a Bunsen… Read More »REACTION OF NON-METALS WITH OXYGEN/AIR

Oxygen is put in cylinders for use where natural supply is not sufficiently enough. This is mainly in: Mountain climbing/Mountaineering-at high altitudes, the concentration of air/oxygen is low. Mountain climbers… Read More »USES OF OXYGEN

The following experiments show the reaction of metals with Oxygen and air. Burning Magnesium Procedure (a) Cut a 2cm length piece of magnesium ribbon. Using a pair of tongs introduce… Read More »REACTION OF METALS WITH OXYGEN/AIR

a) Occurrence. Fifty 50% of the earth’s crust consist of Oxygen combined with other elements e.g. oxides of metals About 70% of the earth is water made up of Hydrogen… Read More »OXYGEN