Physical

What is an ionic bond?

The electrostatic attraction between oppositely charged ions due to electron transfer

Which type of element loses electrons in ionic bonding?

Metals

What happens when a metal loses electrons?

It becomes a positive ion (cation)

Which type of element gains electrons in ionic bonding?

Non-metals

What happens when a non-metal gains electrons?

It becomes a negative ion (anion)

What is the charge of an ion formed when a metal loses electrons?

Positive

What is the charge of an ion formed when a non-metal gains electrons?

Negative

When do ionic compounds conduct electricity?

When molten or dissolved in aqueous solutions

Why can molten ionic compounds conduct electricity?

The ions are free to move and carry charge

Why can ionic compounds conduct electricity when dissolved?

The ions become free to move through the solution and carry charge

Why do ionic compounds have high melting points?

Because it has strong electrostatic attractions between oppositely charges ions which need a large amount of energy to overcome

What is a lattice?

A regular, repeating arrangement of ions

What is an empirical formula?

The simplest whole-number ratio of atoms of each element in a compound

What charge do Group 1 metals form?

+1

What charge do Group 2 metals form?

+2

What charge do Group 3 metals form?

+3

What charge do Group 5 non-metals form?

-3

What charge do Group 6 non-metals form?

-2

What charge do Group 7 non-metals form?

-1

What is a covalent bond?

A shared pair of electrons between two atoms

What does a single covalent bond contain?

One shared pair of electrons E.g: H–H

What does a double covalent bond contain?

Two shared pairs of electrons E.g: O=O

How is a triple covalent bond represented?

With three lines, E.g: N≡N

How many electrons are shared in a triple covalent bond?

Six electrons

What is metallic bonding?

The strong electrostatic force of attraction between positive metal ions in a fixed arrangement and a sea of delocalised electrons

What type of forces act between molecules in a simple molecular structure?

Weak intermolecular forces

Why do simple molecular substances have low melting/boiling points?

weak intermolecular forces between molecules, which require relatively little energy to overcome

Why don't simple molecular substances conduct electricity?

They have no free charged particles available to carry electrical charge

Why are simple molecular substances generally soft/brittle?

Weak intermolecular forces between molecules, so the molecules can be separated relatively easily

What are diamond and graphite?

Allotropes of carbon

How many other carbon atoms is each carbon atom bonded to in diamond?

4

What is the shape around each carbon atom in diamond?

Tetrahedral

Why is diamond very hard?

It contains many strong covalent bonds throughout its giant structure

Why does diamond have a very high melting point?

It is a giant covalent structure, so a large amount of energy is needed to break the strong covalent bonds

Why doesn't diamond conduct electricity?

It has no delocalised electrons or mobile ions to carry charge

How many other carbon atoms is each carbon atom bonded to in graphite?

3

What structure does graphite have?

Hexagonal sheets/layers

Why does graphite conduct electricity?

It has delocalised electron that can move through the layers and carry charge

Why does graphite have a high melting point?

It is a giant covalent structure, so a large amount of energy is needed to break the strong covalent bonds

What type of structure does buckminsterfullerene have?

A simple molecular structure

What is the relative charge of a proton?

+1

What is the relative charge of a neutron?

0

What is the relative charge of a electron?

-1

What is the relative mass of protons and neutrons?

1

What is the relative mass of electrons?

1/1836 ≃ 0

How do you calculate the number of neutrons?

Neutrons = mass number − atomic number

What does the mass number represent?

The total number of protons + neutrons in an atom

What are isotopes?

Atoms of the same element that have the same number of protons but different numbers of neutrons

What is mass spectrometry?

A method of instrumental analysis

What are the five main stages of mass spectrometry?

Ionisation → acceleration → ion drift/flight → detection → data analysis

What can mass spectrometry be used to determine for an element?

The mass and abundance of each isotope

How can mass spectrometry help identify molecules?

By determining their relative molecular mass (Mr)

What does TOF mass spectrometry measure?

The time taken by ions to travel to the detector

What happens during ionisation?

The sample is converted into positive ions

What type of molecules is electron impact ionisation generally used for?

Small molecules

What happens to the sample before electron impact ionisation?

It is vaporised

What is fired at the gaseous sample during electron impact ionisation?

High-energy electrons

What do the high-energy electrons do to the molecules/atoms?

They remove an electron from each molecule/atom

What type of ions are formed during electron impact ionisation?

Positive ions

What is the equation for electron impact ionisation?

M(g) → M⁺(g) + e⁻

Why does electron impact ionisation produce a positive ion?

An electron is removed, leaving the particle with a positive charge

What type of molecules is electrospray ionisation generally used for?

Large molecules

What is the sample dissolved in during electrospray ionisation?

A volatile solvent

What happens to the solution during electrospray ionisation?

It is passed through a fine needle at high voltage

What forms as the solution leaves the needle?

A fine spray of charged droplets

What happens to the solvent in the charged droplets?

The solvent evaporates

How do molecules become positive ions during electrospray ionisation?

Molecules gain H⁺, forming positive ions

What is the equation for electrospray ionisation?

M + H⁺ → MH⁺

What type of ionisation technique is ESI?

A soft ionisation technique (so it doesnt fragment it)

What is the key difference between electron impact and electrospray ionisation?

Electron impact removes an electron from a vaporised sample, whereas electrospray involves adding H⁺ to molecules in solution

What happens to positive ions during acceleration?

They are attracted towards a negative plate

What accelerates the positive ions?

An electric field

What is approximately the same for all ions after acceleration?

Their kinetic energy

What is the equation for kinetic energy?

KE = ½mv²

Which ions travel faster: lower or higher m/z ions?

Lower m/z ions travel faster

Why do lower m/z ions travel faster when ions have approximately the same kinetic energy?

They have a lower mass-to-charge ratio, so they travel at a higher velocity

What happens when ions enter the flight/drift region?

They enter a region with no electric field and travel at constant velocity

Which ions reach the detector first?

Lower m/z ions

What is the equation linking velocity, distance and time?

v = d/t

In TOF mass spectrometry, what happens to time of flight as m/z increases?

Time of flight increases

What happens when positive ions hit the detector?

They gain electrons

What does the gaining of electrons produce?

An electrical current

How does the detector detect the ions?

Positive ions hit the detector and gain electrons, producing an electrical current

What is plotted on the x-axis of a mass spectrum?

m/z

What is plotted on the y-axis of a mass spectrum?

Relative abundance

Why does m/z approximately equal the mass for a singly charged ion?

Because the ion has a charge of +1, so dividing mass by charge gives approximately the ion's mass