Understanding the Periodic Table and Chemical Bonds

Periodic Table of Elements

7s 7p
6s 6p 6d
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s

Elements are sorted by atomic number and grouped by chemical and physical properties, with 18 groups and 7 periods.

Group

A group consists of elements that have a similar electron configuration at the highest energy level. They have the same number of electrons in the same type of sub-levels, although at different energy levels. The chemical characteristics are similar and depend on the outermost electrons of the atoms. There are 18 groups.

Period

A period comprises all elements whose maximum energy level is the same. There are 7 periods: the 1st has 2 elements, the 2nd and 3rd have 8 elements, the 4th and 5th have 18 elements, and the 6th has 32 elements.

Periodic Properties

These are the properties of elements that vary according to the ordering of the elements in the table.

Ionization Energy

Ionization energy is the energy needed to remove an electron from a gaseous atom.

Electron Affinity

Electron affinity is the energy released or required in the process of capturing an electron from an atom. Its variation in groups and periods of the periodic table is similar to ionization energy.

Electronegativity

Electronegativity is the measure of "appetite" of atoms for electrons. On the Lewis scale, it ranges from 0 to 4. Its variation in groups and periods of the periodic table is similar to ionization energy.

Chemical Bonding

Chemical bonding is the union of two atoms that reach a more stable situation than when they are apart.

Bonding Energy

Bonding energy is the energy released in bond formation and the energy to be supplied to break the bond.

Bond Length

Bond length is the distance between two atoms linked by a chemical bond.

Lewis Structure

A Lewis structure is a representation of the valence electrons at the final energy level around the chemical symbol for the element.

Lewis Theory

Atoms are joined to other atoms by gaining, losing, or sharing electrons to acquire the noble gas electron configuration.

Ionic Bond

An ionic bond is a union of positive and negative ions by electrical attraction. They form crystals that are water-soluble and insoluble in some polar solvents. They are solids with high melting temperatures. In solution, they conduct electricity. They are hard, brittle, and inflexible.

Covalent Bond

A covalent bond is a union of two atoms that share a pair of electrons. In very electronegative atoms, the compounds are located between the cores. In sharing, they are noble gases that share a couple of electrons with a single atom. They can be gases or liquids, and their melting and boiling temperatures depend on the forces between molecules. They are soluble in polar or partially polar solvents, forming atomic lattices. They are not conductors of heat and electricity.

Polarized Covalent Bond

A polarized covalent bond is a covalent bond in which the electron pair forming the bond is shifted to one of the most electronegative atoms.

Metallic Bond

A metallic bond is a community liaison of metal atoms in which the valence electrons of two atoms do not bind specifically but participate in a union of all atoms at once. They are oxidizable, have high density, and have not-so-high melting points. They conduct electricity and have a characteristic brightness. Most form alloys and emit electrons.

Hydrogen Bond

A hydrogen bond occurs in molecules with very electronegative atoms bound to hydrogen. It is the attraction of highly electronegative atoms in a molecule by the hydrogen of another molecule.

Van der Waals Forces

Van der Waals forces are attractions between molecules that exhibit electrical polarity, either casual or permanent.