Lecture 5&6- Bonding And Lewis Structure

Question 1

What are the three main types of bonding?

Answer 1

Ionic, Covalent, Metallic

These types of bonding describe how atoms interact to form molecules.

Question 2

Define a molecule.

Answer 2

A neutral entity consisting of two or more atoms held together by chemical bonds

Most often these bonds are covalent.

Question 3

What is the difference between a compound and a molecule?

Answer 3

All compounds are molecules but not all molecules are compounds. Compounds must contain different elements, whereas molecules can contain atoms of the same element

Example: O2 is a molecule, but H2O is a compound.

Question 4

What are the components of an atom?

Answer 4

Nucleus (protons + neutrons), Electrons (surround the nucleus)

Electrons play a principal role in chemical bonding.

Question 5

Why do atoms bond together?

Answer 5

To form a compound that is more stable (has less energy) than the separate atoms

Chemical bonds lower the potential energy between charged particles.

Question 6

What are valence electrons?

Answer 6

Electrons in the outer shell associated with an atom, which can participate in the formation of a chemical bond

Valence electrons are critical for bonding.

Question 7

What is the Octet Rule?

Answer 7

Atoms will gain or lose electrons to achieve the noble gas configuration

The rule applies to elements with valence electrons in the s- and/or p-orbitals.

Question 8

Which elements commonly follow the Octet Rule?

Answer 8

Elements whose valence electrons are in the s- and/or p-orbitals

Does not apply to transition metals or d-block elements.

Question 9

What is valency?

Answer 9

The combining power of an element, related to the number of electrons in the outer shell

Valency is used to predict the formulae of simple compounds.

Question 10

What does univalent mean?

Answer 10

Having a valency of one

Example: H in H2O.

Question 11

What does divalent mean?

Answer 11

Having a valency of two

Example: O in H2O.

Question 12

What is the relationship between valency and oxidation number?

Answer 12

Valency relates to the number of bonds formed, while oxidation number indicates the charge after losing or gaining electrons

Valency has no sign.

Question 13

Describe ionic bonds.

Answer 13

Electrostatic attraction between atoms of opposite charges

Ions form from the complete transfer of electrons.

Question 14

Describe covalent bonds.

Answer 14

Result from the sharing of electrons between two atoms

Common in non-metallic elements.

Question 15

Describe metallic bonds.

Answer 15

Metal atoms bonded to several other atoms with delocalised electrons

Responsible for the lustre and high electrical conductivity of metals.

Question 16

What is electronegativity?

Answer 16

The ability of an atom to attract a shared pair of electrons in its combined state

It determines how atoms bond with each other.

Question 17

What is electropositivity?

Answer 17

The ability of an atom to withdraw a shared pair of electrons in its combined state

This property contrasts with electronegativity.

Question 18

What is the significance of Lewis structures?

Answer 18

Representations of molecules showing all electrons - bonding and nonbonding

They help visualize electron sharing and lone pairs.

Question 19

What does OIL RIG stand for?

Answer 19

Oxidation Is Loss / Reduction Is Gain

A mnemonic to remember the principles of oxidation and reduction.

Question 20

How do you draw a Lewis structure?

Answer 20

1. Find the sum of valence electrons. 2. Write symbols for atoms and connect with single bonds. 3. Complete octets around bonded atoms. 4. Place leftover electrons on the central atom.

If central atom lacks an octet, try multiple bonds.

Question 21

What is a double bond in Lewis structures?

Answer 21

When two electron pairs are shared, represented by two lines

Example: O=C=O for carbon dioxide.

Question 22

What is a triple bond in Lewis structures?

Answer 22

When three electron pairs are shared, represented by three lines

Example: N≡N for nitrogen gas.

Question 23

What are lone pairs?

Answer 23

Pairs of electrons that are not shared with other atoms

They can influence molecular shape and reactivity.

Question 24

What is the role of molecular shape in reactivity?

Answer 24

The shape of a molecule plays an important role in its reactivity

It affects how molecules interact with each other.