Physical and chemical properties of metals and non-metals

Physical and chemical properties of metals and non-metals

There are distinct substances that cannot be spit-up into simpler substances. Such substances consist of only one kind of atom. There are over one hundred elements known to date. Each of the elements is usually symbolized by a capital letter or a capital letter followed by a small letter derived from the English or Latin or Greek name of the element concerned e.g. Hydrogen (H), Sodium (Na), Copper (Cu), Uranium (U), Antimony (SB), Neon (Be), etc.

The elements can be categorized in several ways.

- Based on natural radioactivity, elements are classified into two: radioactive and non-radioactive elements.

Radioactive elements are those that undergo a spontaneous decay or degradation followed by the emission of one or more of the radiations (Alpha, Betta, Gamma).

Such elements include Radium (Ra), Uranium (U), Francium (Fr), Polonium (Po) and Thorium (Th).

Non-radioactive elements do not degrade or emit any radiations. They have stable nuclei and would therefore not undergo radioactive decay e.g. Sodium (Na), Calcium (Ca), etc.

- Based on properties, elements are classified into three: metal, non-metals, and metalloids.

Metals are elements that are ionized by electron loss e.g. Potassium, Sodium, Calcium, lead, etc.

They possess the following physical properties:

i. Ductility and malleability. Hence they are useful in making wire cables and fabrication in construction works.

ii. Good conductor of heat and electricity due to the presence of free mobile electrons in their lattice. They are therefore useful in making cooking pots, boilers and electric cables.

iii. Hard solids with high melting points/boiling points except sodium, which is soft, and mercury, which is a liquid metal.

iv. Lustrous (with silvery colour) hence useful in jewelry and in metallic paints because of its reflectivity.

v. Some of them make a sound note, when struck (sonorous) e.g. copper, iron, and aluminum. Such metals are therefore useful in making musical instruments.

vi. None of the metals are soluble in any ordinary solvent without a chemical change.

The general chemical properties of metal are:

i. Electropositive i.e. loss electron(s) to become ionized hence reducing agents.

ii. Most of the metal s combine with oxygen to form basic oxides e.g. CuO, MgO and CaO. However some metallic oxides are amphoteric e.g. ZnO, PbO. Such oxides react as both acid and base.

iii. Combine with chlorine to form electrovalent chloride e.g. NaCl.

iv. Form metallic hydrides that are ionic.

v. Replace the hydrogen in an acid if more than electropositive than hydrogen.

Non-metals are elements that ionize by electron gain e.g. hydrogen, oxygen, chlorine, bromine, carbon, etc.

Non-metals are therefore oxidizing agents (except a few of them) since they undergo reduction in their ionization process

The general physical properties of non-metals are:

i. Brittle i.e cannot be hammered into sheets (non-mallaeble) or drawn into wires (non-ductile).

ii. Non-conductors of heat and electricity because they do not possess free mobile electrons. However, graphite (a form/allotrope of Carbon) is a good conductor of electricity because it contains free mobile electrons in its lattice.

iii. Mainly gases (e.g. hydrogen, oxygen, nitrogen, chlorine) though some of them exist as solids or liquids. For instance, bromine is a liquid at room temperature, iodine is a soft violet solid, sulphur is a yellow solid, graphite and diamond are solids. While graphite is soft, diamond is the hardest known natural substance.

iv. Most of the non-metals are dull and cannot be polished but diamond (an allotropic firm of carbon) can be polished (lustrous) and can therefore used in jewelry.

v. Non-sonorous.

vi. Have low density though some of them are heavy e.g. diamond.

vi. Some non-metals dissolve slightly in water without reaction (e.g. oxygen) though some of them dissolve with water (e.g. chlorine, bromine).

Some of the general chemical properties of non-metals are:

i. They are mainly oxidizing agents.

ii. Form acidic oxides mainly e.g. carbon(IV)oxide, sulphur(IV)oxide, nitrogen(IV)oxide. The acidic oxides are known as acid anhydrides (compounds that dissolve in water to produce an acidic solution or a solution whose pH is less than 7).

iii. Non-metals combine with other non-metals to form covalent compounds e.g. ammonia, carbon(IV)oxide, hydrogen chloride.