Test 1

Question 0

Define isotopes

Answer 0

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

Question 1

Explain atomic structure

Answer 1

Nucleus contains protons and neutrons
Electrons move around the nucleus in an electron shell

( protons and electrons are equal amount)

Question 2

Give examples of isotopes

Answer 2

• Carbon 12 and Carbon 14 are both isotopes of carbon, one with 6 neutrons and one with 8 neutrons
• Hydrogen 1, 2 and 3
• Oxygen 16, 17 and 18
• Neon 20, 21 and 22

Question 3

Define protons

Answer 3

A stable subatomic particle occurring in all atomic nucleus, with a positive electric charge equal in magnitude to that of an electron.

Question 4

Define neutron

Answer 4

A subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.

Question 5

Define electrons

Answer 5

A stable subatomic particle with a negative charge, found in all atoms in the electron shell.

Question 6

Define electron configuration

Answer 6

Electron configuration refers to the amount of electrons held per electron shell.

Question 7

What is the electron configuration for elements up to 20

Answer 7

2,8,8,2

Question 8

What is the electron configuration for elements 21 to 38

Answer 8

2,8,18,8,2

Question 9

What is the electron configuration for elements 39 to 56

Answer 9

2,8,18,18,8,2

Question 10

Define valence electrons

Answer 10

The electrons in the outermost shell of an atom

Question 11

What is the lewis structure

Answer 11

When the elements symbol is placed in the middle and one dot is drawn to represent each valence electron

Question 12

What are ions

Answer 12

An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Question 13

Explain ion formation

Answer 13

Ions are electrically charged particles formed when atoms lose or gain electrons. They have the same electronic structures as noble gases. Metal atoms form positive ions, while non-metal atoms form negative ions. The strong electrostatic forces of attraction between oppositely charged ions are called ionic bonds.

Question 14

Define relative atomic mass

Answer 14

The ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12.

Question 15

How do you calculate relative atomic mass

Answer 15

Ar(x)= %A x Ar(a) + %B x Ar(b) / 100

Question 16

Define mass spectrometry

Answer 16

Mass spectrometry (MS) is an analytical chemistry technique that helps identify the amount and type of chemicals present in a sample by measuring the mass-to-charge ratio and abundance of gas-phase ions.

Question 17

What 4 stages occur in the mass spectrometer

Answer 17

Ionisation
Acceleration
Deflection
Detection

Question 18

Basic outline of what happens in the mass spectrometer

Answer 18

Atoms and molecules can be deflected by magnetic fields - provided the atom or molecule is first turned into an ion. Electrically charged particles are affected by a magnetic field although electrically neutral ones aren’t. It goes through 4 stages

Question 19

Mass spectrometer: ionisation

Answer 19

The atom or molecule is ionised by knocking one or more electrons off to give a positive ion. This is true even for things which you would normally expect to form negative ions or never form ions at all. Most mass spectrometers work with positive ions.

Question 20

Mass spectrometer: acceleration

Answer 20

The ions are accelerated so that they all have the same kinetic energy.

Question 21

Mass spectrometer: deflection

Answer 21

The ions are then deflected by a magnetic field according to their masses. The lighter they are, the more they are deflected.

Question 22

Mass spectrometer: detection

Answer 22

The beam of ions passing through the machine is detected electrically.

Question 23

Define spectral analysis

Answer 23

The analysis of a spectrum to determine the properties of its source, such as the analysis of the emission spectrum of a substance to determine the electron distribution in its molecules

Question 24

Explain spectral analysis

Answer 24

The energy of each level is different for different elements. As a result, the energy absorbed and released in the electron transitions of a given element are unique for this reason an elements light spectrum is like an atomic fingerprint. When elements are burnt the electrons become excited, when the electrons return to their ground state and emit light of a specific wave length therefore producing specific colours.

Question 25

What is the flame test

Answer 25

Vaporised salts are sprayed into a hot, almost colourless flame causing the electrons to become excited. When they return to their ground state they emit a specific wave length and producing a unique colour. This makes identifying the element much easier.

Question 26

What are some trends of the periodic table

Answer 26

- Arranged horizontally in order of increasing atomic number and vertically in order in order or electron shell configuration. - Elements in the same periods have their outermost electrons in the same shell. - Elements in the same group have the same number of outer shell electrons (therefore similar chemistry)

Question 27

Atomic radius, ionisation energy and electronegativity of an element depend on what

Answer 27

- Core change of outermost electrons | - Average distance of outermost electrons to nucleus

Question 28

Core change:

Answer 28

- The effective positive charge experienced by the outermost electrons in an atom. - Electrons in the inner shells of an atom are thought to have a shielding effect of the positive charge of the nucleus. - Within each group, core charge attracting outermost electrons will be approximately the same.

Question 29

Formula for core change

Answer 29

Core charge = #protons in nucleus - #inner shell electrons

Question 30

Define ionisation energy

Answer 30

Energy required to remove an electron from an atom or an ion. The first ionisation energy of an element is defined as the energy required to remove the outermost electron from one mole of the element in its gaseous state.

Question 31

What does atomic radius depend on?

Answer 31

- # electrons in the atom - shells in which electrons are located - charge on nucleus

Question 32

Atomic radius increasing and decreasing

Answer 32

- Increases down a group | - Decreases across a period

Question 33

First ionisation energy

Answer 33

- Decreases down a group & increases across a period | - Can explain why some atoms lose electrons to form ions more easily than others

Question 34

Electronegativity:

Answer 34

- The electron-attracting power of an atom in a molecule (also applied to ionic compounds and metals) - Increases across a period (atoms smaller / core charge increases) - Decreases down a group (atoms larger / core charge is the same)

Question 35

Define bonding capacity

Answer 35

Bonding capacity of an atom, meaning how many spaces it has left in its valence shell (E.g. Carbon has 4 open spaces left)

Question 36

Define metallic nature

Answer 36

The metallic character of an element can be defined as how readily an atom can lose an electron. From right to left across a period, metallic character increases because the attraction between valence electron and the nucleus is weaker, enabling an easier loss of electrons.