Full Chemistry Paper 1

Charge of a proton

+1

Where is a proton found in an atom?

In the nucleus of an atom

What is the relative mass of a proton?

1

What is a neutron?

A subatomic particle with no charge

Relative charge of a neutron

0 (neutral)

Where is a neutron found?

In the nucleus of an atom

What is the relative mass of a neutron?

1

What is an electron?

A subatomic particle that has a negative charge

What is the relative mass of an electron?

1/1836

Whole atomic structure

a positively charged nucleus, consisting of protons and neutrons, surrounded by negatively charged electrons in shells, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus

why are atoms electrically neutral

as they have the same number of electrons as protons

The negative charge of an electron exactly cancels out the positive charge of a proton

describe the dalton model of the atom

dalton thought atoms were solid spheres that made up all substances, with no internal structure - this model came before the discovery of electrons, protons, or neutrons

J.J. Thompson's model of the atom

the model made by JJ. Thompson, the atom was thought to consist of negatively charged electrons (the ‘plums’) in a positively charged ‘dough’ or ‘pudding’ - the atom was thought to be overall neutral as the negative electrons balanced out the positive ‘dough’

who discovered the electron and how

J.J Thompson discovered the electron by using a cathode-ray tube - he conducted an experiment which identified the electron as a negatively charged subatomic particle, hence proving that atoms are divisible

What was Ernest Rutherford's Gold Foil Experiment and what did it lead hum to discover

rutherford directed a beam of positively charged alpha particles at a thin gold foil and around the foil, he placed a fluorescent screen to detect where the alpha particles went after hitting the foil. most particles went straight through, some deflected and few reflected which led him to hypothesise that most of an atom’s mass is concentrated in a region of space at the centre of the atom called the nucleus

What are alpha particles?

2 protons and 2 neutrons; a helium nucleus with a 2+ charge

James Chadwick's atomic discovery

Discovered the neutron in 1932

Bohr Model

electrons orbit the nucleus in fixed shells or orbitals located at set distances from the nucleus

Each orbital has a different energy associated with it, with the higher energy orbitals being located further away from the nucleus

timeline of changing models of the atom

dalton model

plum pudding model

nuclear model

bohr model

Radius of atom

10⁻¹⁰m

Radius of atom's nucleus

10^-¹⁴ m

Isotopes

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

mass number

the total number/relative mass of protons and neutrons in a nucleus.

atomic number

the number of protons in the nucleus of an atom, unique to each element

Why might the number of electrons be misleading to the atomic number?

Electrons can be gained/lost via ionic bonding, but protons stay the same.

Why might the relative atomic mass of elements in the periodic table be displayed as a decimal?

it depends on the mass number and abundance of isotopes

how to calculate number of neutrons in an atom

mass number - atomic number

How to calculate relative atomic mass

(isotopic mass 1 x % of 1) + (isotopic mass 2 x % of 2) / 100

similarities of isotopes

- same number of protons
- same number of electrons
- same chemical properties

Differences in Isotopes

- Different masses
- Different number of neutrons
- Nuclear stability may vary
- physical properties

electronic configuration

the arrangement of electrons in an atom

Why can't chemical reactions be used to create different elements?

chemical reactions don't affect atom nuclei.

Which subatomic particles take part in chemical reactions?

electrons

mass number vs relative atomic mass

mass number is a whole number as there is a whole number amount of protons and neutrons, however RAM can be a decimal as it is an average of the relative mass and abundance of isotopes

The vertical columns on the periodic table are called

groups

The horizontal rows on the periodic table are called

periods

Electronic configuration of first 3 shells

1st shell - 2
2nd shell - 8
3rd shell - 8

What do elements in the same group have in common?

same number of outer shell electrons and similar chemical properties

What do elements in the same period have in common?

same number of energy shells

How did Mendeleev organize his periodic table?

he organised the elements into vertical columns based on their properties and the properties of their compounds. he then started to arrange them horizontally in order of increasing mass number and as he worked, he found that a pattern began to appear in which chemically similar elements fell naturally into the same columns

how did mendeleev predict the existence of undiscovered elements

He used the properties and trends of other elements in the group with the gap to predict the properties of these undiscovered elements

differences in modern periodic table and mendeleevs table

mendeleev organised elements by increasing mass number, modern is by increasing atomic number

mendeleev left gaps for undiscovered elements

Ionic bonding occurs between...

metals and non-metals

metals tend to form ------- when ionically bonding

cations (positive ions)

this means they have lost electrons

non-metals tend to form ------- when ionically bonding

anions (negative ions)

this means they have gained electrons

Why do electrons transfer in ionic bonding?

To create a full outer shell of both elements

dot and cross diagrams

Used to model the electrons in chemical bonding.

How is the transfer of electrons shown in dot and cross diagrams?

Arrows are used to show the transfer of electrons from metal to non-metal.

What notation is used to indicate the charge of atoms in dot and cross diagrams after electron transfer?

Enclosing the atom diagrams in square brackets with the charge at the top.

Ion

electrically charged atom or group of atoms formed by the loss or gain of electrons

If the electron number of a 2+ ion is 68, what is the atomic number?

70

Ionic structure

Giant ionic lattice, consisting of a regular arrangement of ions, held together by the strong electrostatic forces of attraction between oppositely charged ions

How do non metals in an ionic compound differ in their naming

they have an -ide ending, for example, silicide, fluoride, chloride

Compound ions with oxygen end in..

-ate

Sulfate charge

SO₄²⁻

Carbonate charge

CO₃²⁻

Nitrate charge

NO₃⁻

Ammonium charge

NH₄⁺

hydroxide charge

OH⁻

Silver charge

Ag⁺

Zinc charge

Zn²⁺

lead charge

Pb²⁺

Copper charge

Cu²⁺(usually)

Group 1 charge on ion

1⁺

Group 2 charge on ion

2⁺

Group 3 charge on ion

3⁺

Group 5 charge on ion

3⁻

Group 6 charge on ion

2⁻

Group 4 charge on ion

4⁺/4⁻

Group 7 charge on ion

1⁻

Where does covalent bonding occur?

between 2 non-metals

Molecule

two or more atoms held together by covalent bonds

how does a covalent bond form

Non-metal atoms can share electrons with other non-metal atoms to obtain a full outer shell of electrons. When atoms share pairs of electrons, they form covalent bonds

diatomic molecule

A molecule consisting of two atoms

how to remember diatomic molecules

BrINClHOF

bromine, iodine, nitrogen, chlorine, hydrogen, oxygen, flourine

What holds covalent bonds together?

electrostatic attraction between the positively charged nuclei of two atoms and the negatively charged shared pair(s) of electrons located between them

What is a correlation between the number of shared pairs of electrons and the ionic charge of the element?

they are equal
For example nitrogen has a 3- charge, and shares 3 pairs of electrons

dot and cross diagram for hydrogen

dot and cross diagram for hydrogen chloride

dot and cross diagram for water

dot and cross diagram for methane

dot and cross diagram for oxygen

dot and cross diagram for carbon dioxide

properties of ionic compounds

high mps and bps

water soluble

can conduct electricity

why do ionic compounds have high mps and bps

A lot of energy is required to break the strong electrostatic forces of attraction between oppositely charged ions

why are ionic compounds water soluble

due to the attractions between polar water molecules and the ions, which allows the water molecules to pull the ionic lattice apart

why do ionic compounds conduct electricity (when molten)

Ionic compounds can conduct electricity in the molten state or in solution as they have ions that can move and carry charge

properties of covalent substances

low mps and bps so covalent compounds are usually liquids or gases at room temperature

insoluble

cannot conduct electricity

why do covalent substances have low mps and bps

the weak intermolecular forces are easily overcome, meaning that these compounds are usually volatile

why are covalent substances insoluble

they tend to be non-polar but can dissolve in organic solvents

why do covalent substances not conduct electricity

all electrons are involved in bonding so there are no free electrons or ions to carry the charge

Allotropes

different molecular structures of the same element in the same state

allotropes of carbon

diamond, graphite, graphene, buckminsterfullerene

Giant covalent structure

many non-metals atoms bonded to other non-metal atoms via strong covalent bonds

properties of giant covalent substances

high mps and bps

most cannot conduct electricity

why do giant covalent substances have high mps and bps

as they have many strong covalent bonds and large amounts of heat energy are needed to overcome these forces and break down bonds

why do most giant covalent substances not conduct electricity

Most cannot conduct electricity as they do not have free electrons but there are some exceptions such as graphite

structure of metals

Metals consist of metal atoms held together strongly by metallic bonding

Within the metal lattice, the atoms lose their valence electrons and become positively charged

The valence electrons no longer belong to any metal atom and are said to be delocalised, creating what is known as a sea of free electrons

The free electrons move freely in between the positive metal atoms

properties of metals

very strong - high mps and bps

insoluble in water

can conduct

malleable and ductile

why are metals strong and have high mps and bps

as a result of the attraction between the positive metal ions and the negatively charged delocalised electrons. A lot of heat energy is needed to overcome forces and break these bonds