C1&2 Atomic structure and Periodic Table

Question 1

What is an element

Answer 1

a substance with only one type of atom

Question 2

What are groups

Answer 2

Columns in the periodic table containing elements with the same number of atoms on the outer shell

Question 3

What are periods

Answer 3

Rows in the periodic table that contain elements with the same number of electron shells

Question 4

What is an ion

Answer 4

an atom that has lost or gained electrons and has an overall charge

Question 5

what is the atomic number of an atom

Answer 5

the number of protons in the atom (bottom number)

Question 6

What is the mass number of an atom

Answer 6

The total number of protons and neutrons in the atom (top number)

Question 7

what are isotopes

Answer 7

isotopes are different forms of the same element which have the same number of protons but different number of neutrons

Question 8

What is the formula for working out the relative atomic mass of elements

Answer 8

sum of (isotope abundance x isotope mass number) / sum of abundance’s of all the isotopes (100)

Question 9

What is a compound

Answer 9

compounds are make from two or more different elements combined together in fixed proportions and they’re held together by chemical bonds

Question 10

What is a mixture

Answer 10

consists of two or more elements or compounds which are not chemically combined together

Question 11

What is the method of distillation

Answer 11

Liquid boils off and condensed in the condenser. the thermometer will read the boiling point of the pure liquid and the vapour is cooled and condensed back to liquid and is collected

Question 12

What mixture is separated by simple distillation

Answer 12

soluble salt dissolved in a liquid

Question 13

what type of mixture is separated by crystallisation / evaporation

Answer 13

a soluble solid and a liquid

Question 14

Evaporisation method

Answer 14

pour the solution into an evaporating dish and slowly heat the solution and the solvent will evaporate and the solution will get more concentrated. Crystals will form and keep heating the fish until all that is left are dry crystals

Question 15

Crystallisation method

Answer 15

Pour solution into evaporating dish and gently heat. Once some of the solvent evaporates crystals start to form (the point of crystallisation is reached) take the dish off the heat and leave to cool. The salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution. Filter the crystals out of solution or leave in a warm place to dry

Question 16

Type of mixture separated by filtration

Answer 16

an insoluble solid in a liquid

Question 17

type of mixture separated by chromatography

Answer 17

a mixture of dissolved substances

Question 18

Method of Chromatography

Answer 18

Line is drawn in pencil by the bottom of filter paper. A spot of ink is placed on the line and the sheet is placed in a beaker of solvent. Place a lid on the beaker to stop solvent evaporating. The solvent seeps you the water carrying ink with it and each different dye will move up the paper at a different rate so the dye separates and forms dots in different places. Once solvent has reached the top, dry paper.

Question 19

Type of mixture separated by fractional distillation

Answer 19

Soluble liquids with different boiling points

Question 20

Method of Fractional distillation

Answer 20

Mixture of liquids is heated and all liquids evaporate at different temperatures. the liquid with the lowest boiling point evaporated first and when the temperature on the thermometer reaches the boiling point it will reach the top of the column. The fractionating column has a temperature gradient so the liquids with higher boiling points might start to evaporate but will condense before they reach the cooler top. Liquid then passes through a condenser and is collected. Once first liquid has been collected you raise the temperature until the next one reaches the top

Question 21

What did John Dalton do

Answer 21

In the 19th century John Dalton described atoms as solid spheres and said that different spheres make up different elements

Question 22

What did JJ thomson conclude

Answer 22

Plum Pudding model theory that atoms were a ball of positive change with negative electrons embedded in it

Question 23

what experiment did Ernst Rutherford and Marsden carry out? and what were his results?

Answer 23

They fired positively charged alpha particles at an extremely thin sheet of foil and were expecting the particles to pass straight through the foil or be slightly deflected. However although some passed through, many were deflected and a small number were deflected backwards

Question 24

What did the experiments lead Rutherford to conclude?

Answer 24

The mass of the atom is concentrated at its centre with is positively charged and the nucleus is surrounded by a ‘cloud’ of negative electrons. When alpha particles come near the nucleus they are deflected and when they hit the nucleus they are deflected backwards

Question 25

What was Niel Bohr’s theory of the atom?

Answer 25

Scientists realised that a ‘cloud’ of electrons would be attracted to the nucleus and cause the atom to collapse. Niel Bohr’s model suggested that electrons were contained in shells and orbit the nucleus in their fixed shells

Question 26

What did later experiments of the atom and the work of James Chadwick conclude?

Answer 26

The idea that the positive charge of the nucleus can be subdivided into a whole number of smaller charge with each particle having the same amount of positive charge - protons. James Chadwick showed the existence of neutrons within the nucleus

Question 27

How many electrons fit on each shell

Answer 27

First energy level - 2 Second energy level - 8 Third energy level - 8

Question 28

How was the periodic table arranged before the discovery of protons, neutrons and electrons?

Answer 28

Scientists attempted to classify elements by arranging them in their order of atomic weights and their properties were not taken into consideration

Question 29

what did Mendeleev do to the periodic table

Answer 29

He left gaps for elements he thought had not been discovered and in some places he changed the order based on atomic weight if the order of properties meant it should be changed. Elements with properties Mendeleev predicted were later discovered and filled the gaps.

Question 30

How is the modern periodic table arranged

Answer 30

Isotopes of the same element have different atomic masses but same chemical properties so occupy the same position in the periodic table. Arranged in order of atomic (proton) number so that elements with similar properties are in columns known as groups. Elements in the same group (column) have the same number of electrons on their outer shell and elements in the same period have the same number of shells. Metals are found towards the right and top of the periodic table

Question 31

What happens to noble gases as you go down the group?

Answer 31

•Boiling points increase due to in increase in electrons which means greater intermolecular forces to overcome

Question 32

Properties of group 0 (noble gases)

Answer 32

Full outer electron shells | Unreactive and do not easily form molecules

Question 33

Properties of Group 1 (alkali metals)

Answer 33

* Soft * low density (first 3 are less dense than water) * all have one electron on outer shell * Very reactive

Question 34

What happens to alkali metals as you go down the group

Answer 34

* Increasing reactivity as the outer electron is further away from nucleus so weaker attraction * Lower melting and boiling points * Higher relative atomic mass (larger atom) * Outer electron is lost more easily

Question 35

Alkali metals reaction with water

Answer 35

React vigorously to produce hydrogen gas and metal hydroxides

Question 36

Alkali metals reaction with chlorine

Answer 36

React vigorously when heated in chlorine gas to form white metal chloride salts

Question 37

Alkali metals reaction with oxygen

Answer 37

React to form a metal oxide. This means they tarnish and a full metal oxide layer is formed in air. This is why they are stored under oil to stop them reacting with oxygen (or water) in air

Question 38

Alkali Metals compared to transition metals

Answer 38

* Alkali metals are more reactive * Alkali metals are less dense, strong and hard * Alkali metals have lower melting points

Question 39

Properties of group 7 - Halogens

Answer 39

* Have 7 electrons on outer shell * Have coloured vapours * Consist of molecules made up of pairs of atoms (Cl2) * Form ionic salts with metals (-1 charge) * Form molecular (simple covalent) compounds with other non-metallic elements

Question 40

What happens to group 7 as you go down the group?

Answer 40

* Halogens become less reactive as it’s harder to gain an extra electron due to weaker attraction forces * Have higher melting and boiling points * Have higher relative atomic masses

Question 41

What happens in displacement reactions

Answer 41

A more reactive halogen will displace a less reactive halogen from an aqueous solution of its salt. e.g. chlorine will displace bromine and iodine for an aqueous solution of its salt

Question 42

Properties of Transition metals

Answer 42

* Good conductors of heat and electricity * Very dense, strong and shiny * Do not react vigorously with water or oxygen * Have ions with different charges * Have coloured compounds * Are useful as catalysts