Week 0 - Atomic Structure & Bonding (Ch.2)

Question 1

Mass of proton & neutrons?

Answer 1

1.67 x 10^-27 kg

Question 2

Mass of an electron?

Answer 2

9.11 x 10^-31 kg

Question 3

Atomic mass

Answer 3

Protons + # Neutrons

Question 4

Atomic number (Z)

Answer 4

Protons -> gives the chemical identification of an element

Question 5

Isotope number

Answer 5

Neutrons

Question 6

Atomic mass unit (amu)

Answer 6

1 amu = 1/12 mass of Carbon-12

Protons + # Neutrons = # amu

Question 7

Atomic weight (A)

Answer 7

The weighted average of atomic masses of naturally occurring isotopes.

Usually measured in mass per mole.

Question 8

Isotopes

Answer 8

Isotopes are atoms with different atomic masses which have the same atomic number. They have a different number of neutrons in the nucleus.

Question 9

Mole

Answer 9

Amount of substance that contains the same number of atoms/molecules/particles as in 12g of Carbon-12.

1 Mole = 6.022 x 10^23 atoms/molecules/particles

(A way of grouping together atoms like we have words for pair, dozen, trio etc.)

Question 10

Atoms

Answer 10

Made up of the nucleus which contains protons and neutrons, then surrounded by orbiting rings of electrons.

Question 11

What are the 2 atomic models and what are the differences?

Answer 11

They are the Bohr model and wave-mechanical model.

Bohr’s model talks about discrete levels of energy within the electron shells whereas they are continuous values in the wave model.

Bohr’s model tells us that electrons have particle like properties, whereas in the wave model it tells us that it has properties of both a wave and a particle.

Question 12

What is the quantum mechanical principle which relates to the energy of electrons?

Answer 12

Energies of electrons are quantized, only specific values of energies are allowed

Question 13

What are the different types of bonding?

Answer 13

They are split into primary and secondary bonding.

Primary consists of ionic, covalent and metallic bonding.

Secondary bonding is also known as van der Waals bonding.

Question 14

Which common materials use which type of bonding?

Answer 14

Metal - metallic
Ceramic - ionic/mixed ionic-covalent
Polymer - covalent
Molecular solids - van der Waals
Semimetals - mixed covalent-metallic
Intermetallics - mixed metallic-ionic

Question 15

Ionic Bonding

What elements does this occur with, what do they form and does it have a direction?

Answer 15

A giving/taking of electrons to form compounds. This typically occurs between metals and non-metals.

This form of bonding is non-directional meaning that because one electron has been given/taken, direction doesn’t matter because of the electrostatic force of attraction between the 2 atoms. (Like it’s in equilibrium)

Question 16

Covalent Bonding

What elements does this occur between, what does it create and is it directional?

Answer 16

A sharing of electrons which usually occurs between non-metals. This creates a molecule.

This form of bonding is directional

Question 17

Metallic Bonding

In which elements does this occur?

Answer 17

The strong attraction between closely packed positive metal ions and a ‘sea’ of delocalised electrons.

Typically occurs between metals.

Question 18

Secondary / van der Waals Bonding

Answer 18

A weaker bond than primary, which arises from molecular dipoles attracting to one another.

Question 19

Ion

Answer 19

An atom with a charge denoted by +(number) next to the element.

The net charge can be found by #Protons - #Electrons

Question 20

Electronegativity

Answer 20

How badly an atom wants to take electrons.

It wants to accept electrons to then form a negative ion.

High electronegativity is found in non-metals and lower in metals.

Question 21

Electropositivity

Answer 21

How badly an atom wants to give electrons.

It wants to give electrons to then form a positive ion.

Question 22

Mixture

Answer 22

The result of combining 2 or more substances together.

Eg: concrete

Question 23

Substance

Answer 23

A solid, liquid or a gas

Question 24

Alloy

Answer 24

A metal made by combining 2 or more metallic elements together.

Question 25

Hydrogen Bonding

Answer 25

A form of secondary bonding between hydrogen and certain elements with high electronegativity.

This means H will be positive when connected to something with a high electronegativity and wants to attract to something with a negative charge.

This is only the case with direct connections as in other cases hydrogen is sharing its electrons with other parts of the molecule with covalent bonding.

Question 26

What can hydgrogen form a hydrogen bond with?

Answer 26

Oxygen, Fluorine & Nitrogen

Question 27

Ground State

Answer 27

The lowest energy level of an electron

Question 28

Fluctuating Dipole Bonds

Answer 28

Atoms have a vibration which can cause them to temporarily change from a normal atom to a dipole. When this happens, the electric dipole can induce others to also make them dipoles and in turn creates a van der Waals bond.

Question 29

Polar Molecule-Induced Bonds*

Answer 29

An asymmetrical distribution of electrons is known as a polar molecule and has a permanent dipole. This can include other molecules and create a bond due to an attractive force.

Question 30

Permanent Dipole Bonds*

Answer 30

An attractive force between 2 polar molecules.

This is found most commonly in hydrogen bonding.