Chemical bonding

Question 1

Chemical bonds

Answer 1

forces that hold atoms together to make compounds or molecules.
Chemical bonds include covalent, polar covalent, and ionic bonds

Question 2

Lewis Structure

Answer 2

very simplified representation of the valence (outer shell) shell electrons in a molecule.
It is used to show how the electrons are arranged around individual atoms in a molecule.
Electrons are shown as “dots” or for bonding electrons as a line between the two atoms.

Question 3

Ionic Bonding

Answer 3

Ions are formed when valence electrons are transferred from one atom to another.
The simplest ions are single atoms which have either lost or gained 1,2 or 3 electrons so that they’ve got a full outer shell.
This bond usually occurs between metals and non - metals

Question 4

Hydrogen Bonding

Answer 4

strongest intermolecular force
In order for a hydrogen bond to occur there must be both a hydrogen donor and an acceptor present.
The donor in a hydrogen bond is usually a strongly electronegative atom such as N, O, or F that is covalently bonded to a hydrogen bond.

Question 5

hydrogen acceptor

Answer 5

electronegative atom of a neighbouring molecule or ion that contains a lone pair that participates in the hydrogen bond

Question 6

Hydrogen bonding occurs in organic molecules

Answer 6

N-H groups
Examples range from simple molecules like CH3NH2 (methylamine) to large molecules like proteins and DNA. The two strands of the famous double helix in DNA are held together by hydrogen bonds between hydrogen atoms attached to nitrogen on one strand, and lone pairs on another nitrogen or oxygen on the other one

Question 7

Covalent Bonding

Answer 7

two atoms (usually non metals) share their valence (outermost) electrons, so they’ve got a full outer shell of
electrons.
A single covalent bond contains a shared pair of electrons.

Question 8

Co-ordinate (Dative) bonds

Answer 8

one of the atoms provides both of the shared electrons

Question 9

Nonpolar Covalent Bond

Answer 9

A bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair.

Question 10

Polar Covalent Bond

Answer 10

A bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair
a bond where the electron pair is displaced toward the
more electronegative atom
atom then obtains a partial-negative charge while the less electronegative atom has a partial-positive charge.
This separation of charge or bond dipole can be illustrated using an arrow with the arrowhead directed toward the more electronegative atom.
has some ionic properties

Question 11

Dipole - Dipole Forces

Answer 11

Occur between the positive end of one polar molecule and the negative end of another polar molecule.
They are much weaker than ionic or covalent bonds and have a significant effect only when the molecules involved are close together (touching or almost touching)

Question 12

London dispersion forces

Answer 12

weak intermolecular interaction arising from induced instantaneous dipoles in molecules; part of the Van der Waals forces

Question 13

Dipole

Answer 13

Any molecule that has both a slightly positive and negative charge on either end.
Dipoles generally occur between two nonmetals that share electrons as part of their bond.

Question 14

Van der Waals forces

Answer 14

sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds, or the electrostatic interaction of ions with one another, with neutral molecules, or with charged molecules

Question 15

Examples of
van der Waals forces

Answer 15

hydrogen bonding
London dispersion forces
dipole-dipole interactions

Question 16

Why do some elements undergo ionic bonds while others form covalent bonds

Answer 16

If the electronegativity difference is too high (greater than 1.7) then an electron will be gained by one element forming an anion and the element from which the electron has been lost will become cation. This is an ionic
bond.
However if electronegativity of the two elements is similar then the electron cloud will remain in between two elements neither of them will gain an electron or lose an electron, so a covalent bond will form.