Chemistry Elements Of Life Definitions

Front 1

Atomic number

Back 1

The number of protons/electrons

Front 2

Mass number (RAM)

Back 2

The number of protons plus neutrons. It is an average of relative isotopic masses and abundances.

Mass number = (abundance x A_r of isotope_1) + (abundance x A_r of isotope_2) + ... ÷ 100

Front 3

Isotope

Back 3

Atoms of the same element but with a different mass number. Because of a different number of neutrons.

Front 4

Tritium

Back 4

H- 3,1

Front 5

Relative intensity to relative abundance

Back 5

1) Measure height of the peak for required isotope

2) Add up the total height for all the peaks

3) (required isotope height ÷ total height) × 100

Front 6

Hydrogen

Back 6

H- 1,1

Front 7

Deuterium

Back 7

H- 2,1

Front 8

Mass spectroscopy

Back 8

This is where a mass spectrometer measures the masses of small amounts of substances

1) Vaporisation

2) Ionisation

3) Acceleration

4) Deflection

5) Detection

6) Amplification

7) Recording

Front 9

Nuclear fusion

Back 9

Where two nuclei with low masses combine to produce a single nucleus with a higher mass and this releases energy and sub atomic particles and happens under extremely high temperatures in the 'heart' of stars.

Front 10

Electromagnetic spectrum

Back 10

Gamma. High frequency

X-ray

Ultra violet

Visible light

Infra red

Microwaves

Radio waves. Low frequency

Front 11

Emission spectra

Back 11

This is the light that is formed when electrons get excited and jump to a higher energy level and then as they drop to their original level they emit energy as EM radiation.

Front 12

Lavoisier

Back 12

He published a list of elements and ordered them by their properties.

The problems were:

*It was written in French (so some people didn't understand it)

*Some things that were included were not actually elements (eg light!)

Front 13

Döbereiner

Back 13

He was a German scientist that grouped the elements into groups of threes because of similar properties. He called the threes triads. He also saw that the atomic mass of the two outer elements averaged to be the atomic mass of the middle one.

The problems were:

* Some elements didn't fit

* Sometimes new elements were discovered and they sometimes made groups of four.

Front 14

Newlands

Back 14

He was an English scientist who put the elements into groups of eight called octaves because each 8th element was similar

The problems were:

* His model only worked for the first 20 elements

* Some of the elements were wrong

Front 15

Mendeleev

Back 15

He was a Russian scientist who put the names of elements on cards and arranged them by properties and atomic weight. And he left space in his model so that undiscovered elements could be put in. His model is what the modern periodic table is based on.

Front 16

First ionisation energy

Back 16

The amount of energy required to remove the outermost electron.

Front 17

Factors affecting ionisation energy

Back 17

1) charge of the nucleus - more protons = more energy (because of stronger attraction)

2) distance from electron to nucleus - larger distance = lower energy (because of lower attraction)

3) the number of electrons between the outer electron and the nucleus (shielding) - more electrons = lower energy (because of weakened electrostatic attraction)

4) if the outer electron is paired or on its own - paired electrons = lower energy (repulsion between the two)

Front 18

Ionic bonding

Back 18

Bonding between a metal and a non metal. Forms strong electrostatic attraction between the elements and the electrons are transferred. Only conduct electricity when liquids because the electrons need to be free.

Front 19

Covelant bonding

Back 19

This is bonding between a non metal and a non metal and involves sharing electrons. There are two types of covelant bonding, simple and giant.

Front 20

Simple covelant bonding

Back 20

This forms a bond and these have low melting points, they form weak bonds and are insulators

Front 21

Giant covelant bonding

Back 21

These are strong bonds and have high melting/boiling points they don't conduct electricity ( graphite is an anomaly because it is carbon based and each carbon makes 3 bonds so there is a free electron and this means it will conduct electricity.

Front 22

Metallic bonding

Back 22

This is bonding between a metal and a metal. They have high boiling/melting points, they are strong, malleable, ductile and good conductors of heat and electricity.

Front 23

Lone pairs

Back 23

These are a covelant bond and they are the pairs that are not being shared.

Front 24

Bonding pairs

Back 24

These are a bond in a covelant bond and they are pairs that share electrons. Eg. Carbon monoxide.

Front 25

Dative pairs

Back 25

This is a shared pair but where both the electrons come from the same atom.