Atoms Case

1. What is an atom? Structure? Composition? Give an example. Draw an atom.

Atom - is the basic unit of an element. An atom is a form of matter which may not be further broken down using any chemical means. A typical atom is composed of three subatomic particles: protons, neutrons and electrons.

Examples:

Neon, Ne

Hydrogen, H

Plutonium, Pu

Protium, an isotope of hydrogen

Calcium ion, Ca2+

2. What is ionic bond? Covalent? Give an example. How is this formed?

Ionic bond - is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed due to the attraction between an atom that has lost one or more electron (known as a cation) and an atom that has gained one or more electrons (known as an anion). Usually, the cation is a metal atom and the anion is a nonmetal atom.

Examples:

NaBr - sodium bromide

KBr - potassium bromide

NaCl - sodium chloride

NaF - sodium fluoride

KI - potassium iodide

KCl - potassium chloride

CaCl2 - calcium chloride

K2O - potassium oxide

MgO - magnesium oxide

Covalent bond - is the chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.

Covalent bonds form when two non-metals share an electron. Covalent bonds occur when non - metal elements have an unstable outermost shell known as the valence electrons. The two non-metals either give up or gain electrons and then live with the other element or elements outer shell.

Examples:

O3 - ozone

H2 - hydrogen

H2O - water

HCl - hydrogen chloride

CH4 - methane

NH3 - ammonia

CO2 - carbon dioxide