C1.1 - C1.8 Atoms,bonding,moles✔️

Question 1

What is an element?

Answer 1

Substance made of only one type of atom

Question 2

What does each group contain?

Answer 2

Elements with similar chemical properties - and electrons in outer shell

Question 3

What are compounds?

Answer 3

2 or more different types of elements bonded together - chemical bonds hold atoms tightly

Question 4

Law of conservation of mass?

Answer 4

The total mass of the products formed in a reaction is equal to the total mass of reactants

Question 5

What is aqueous solution?

Answer 5

Substances dissolved in water - (‘aq’ is the symbol)

Question 6

What is an atom?

Answer 6

Atom smallest part of an element that can exist

Question 7

What is filtration?

Answer 7

Technique used to seperate substances that are insoluble in a particular solvent from those that are soluble

Question 8

What were Dalton ideas/beliefs about atoms?

Answer 8

-In chemical reactions - atoms rearanged themselves and combined with other atoms
-atoms could not be divided or split

Question 9

What was JJ Thomson discovery?how did he discover it?

Answer 9

-End of 1800s discovered the electron
-experimenting by applying high voltages to gasses at low pressure
-electons negativley charged

Question 10

What were the elements origionaly ordered in the early perodic table?

Answer 10

By order of atomic mass however early perodic table incomplete because not all elements were discovered

Question 11

Thomsons plum pudding model?

Answer 11

Negative electrons embedded in a cloud of positive charge - like bits of plum in a plum puding

Question 12

What was Niels bohrs suggestion/idea ?

Answer 12

Electrons orbit the nucleus - at fixed energy levels(shields)

Question 13

What did James Chadwick disscover?

Answer 13

1932 - disscovered neutrons

Question 14

What is an ion

Answer 14

An ion is a charged atom or group of atoms

Question 15

What is an isotope?

Answer 15

Atoms of the same element with different number of neutrons - same atomic number but different mass number

Question 16

Properties of isotopes?

Answer 16

-different density
-may be radioactive
-always have same chemical properties - same number of electrons - electronic stucture unchanged

Question 17

How can mixtures be seperated?

Answer 17

Seperated by physical means such as filtration,crystallisation and simple distlation

Question 18

What is a mixture?

Answer 18

Mixture is made up of two or more substance that are not chemically combined together

Question 19

What is paper chromatography?

Answer 19

A technique used to seperate and indetify substances from mixtures in solutions

Question 20

How does paper chromatography seperate mixtures?

Answer 20

Seperates mixtures of substance dissolved in a slovent as they move up a piece of chromatography paper

Question 21

How do you obtain crysals through crystalisation?

Answer 21

To obtain a sample of pure salt you would need to filter the solution then heat with a bunsern burner until point of crystalisation and then leave the rest to evaporate in a flat bottom dish like a petri dish to give a large surface area for water to evaporate from

Question 22

How do you know a soluion is at the point of crystalisation?

Answer 22

Crystals first appear arround the edges of the solution or on a drop of solution extracted with a glass rod

Question 23

Define crystalisation?

Answer 23

Seperating a soluble solid from a solvent to produce samples of pure salt

Question 24

Explain the process of distilation?

Answer 24

1)solution is heated and boiled to evaporate the solvent
2)vapour then enters a condenser
3)condenser is an outer glass tube with water flowing through it and acts as a cooling “jacket” arround the inner glass tube
4)vapour condenses and turns back into liquid
5)collected in a flash/beaker

Question 25

Uses of distilation?

Answer 25

In countries where there is a lack of fresh water sources - They can purify sea water to obtain drinkable water

Question 26

What is a condenser used in distilation?How does it work?

Answer 26

condenser is an outer glass tube with water flowing through it and acts as a cooling “jacket” arround the inner glass tube - vapour enters and cools and condenses back into a liquid

Question 27

Define a mixture?

Answer 27

Mixture - made up of two or more substances that are not chemicaly combined - no chemical bonds between atoms of different substances

Question 28

How can elements in a compound be seperated?

Answer 28

Chemical reaction must be used to seperate the elements

Question 29

4 physical methods to seperate mixtures?

Answer 29

-filteration
-crystalisation
-distillation
-chromatography

Question 30

Explain how paper chromatography seperates mixtures?

Answer 30

Substances dissolved in a solvent move up a piece of chromatogtaphy paper and the different substances are seperated because of their different solubilities in the solvent used

Question 31

When did JJ Thomsom descover the electron?

Answer 31

End of 1800s

Question 32

How did JJ Thomson discover the electron?

Answer 32

Applyed high voltages to gases at low pressure and did experiments on the beams of particles - they were attracted to positive chage shwoing they must be negativley charged

Question 33

Why was it hard for James chadwick to discover the neutron?

Answer 33

Neutrons have no charge therefore they are very difficult to detect only when he did an experiment that could only be explained by the existence of neutrons

Question 34

What was Geiger and marsdens experiment,and what did it lead to?

Answer 34

Experimenting with radioactive particles by firing dense positivley charged particles (alpha particles) at a thin piece of gold foil expecting all to go through instead not all did suggestig the plum pudding model was wrong

Question 35

What is atomic number?

Answer 35

Number of protons - equal number of electrons and protons

Question 36

What is mass number?

Answer 36

Number of protons + neutrons

Question 37

What is the insoluble solid that remian behind during filtaration?

Answer 37

Residue

Question 38

Define distilation?

Answer 38

Used to seperate and recover a solvent from a solute

Question 39

Why is fractional distillation an effective way of seperating miscible liquids?

Answer 39

Allows you to seperate and collect the liquid with the lowest boiling point as the miscible liquids will have different boiling points