chemistry unit 1

John dalton year

1808

John dalton theory

all matter made of atoms, atoms have different masses, same element have same mass and properties, compounds formed when 2 or more atoms combined

John dalton model

bowling ball

JJ Thomson year

1897

JJ Thomson's discovery

cathode ray is used to discover all atoms contain negative subatomic particles, because it has a neutral charge this means there must also be positive particles

JJ Thomson model

Plum pudding model

Ernest Rutherford year

1910

Ernest Rutherford method of discovery

beam of alpha particles through a sheet of gold foil

Ernest Rutherford discovery

most of atom is empty space, positive nucleus in the middle, electrons orbit nucleus similar to planets orbiting sun, proved nucleus existed

James Chadwick year

1932

James Chadwick contribution

showed neutron was distinct particle, disproved pairing of proton and neutron

Neils bohr year

1913

Neils Bohr discovery

electrons travel in waves around the nucleus in circular orbits with discrete radii, when electron moves from an exited level back to another level it emits energy in the form of light wavelength

what type of attraction holds electrons to nucleus

electrostatic attraction

order of theorists

dalton, thomson, Rutherford, Chadwick, Bohr

Who discovered the electron

JJ Thomson

Who discovered proton

Rutherford

Who discovered neutron

Chadwick

How is the periodic table organised

By atomic number

Main difference between Rutherford and boys models

Boys idea was that the energy possessed by electrons can only exist as certain values

What is spectroscopy the study of

Interaction between matter and electromagnetic radiation

Steps of spectrometry

Vaporise, ionise, accelerate, deflect, analyse/ detect

Internal validity

Accuracy of the study’s results within the specific study, setting ensures observed effect is due to independent variable

External validity

The generalisability of the findings to other populations, settings, and conditions beyond the study

Elements of similar properties are found in

The same group

Group 1

alkali metals

Group 2

alkali Earth metals

Group 17

Halogens

Group 18

Noble gases

Why is it that across a period no. Subatomic particles in an atom increases but the size decrease

The additional nuclear charge attracts the electrons more strongly during them closer to the nuclear so decreasing the size of the atom and Across a period the number of shells stays the same

why does each element have its own spectra?

Electrons ability to release energy as they move from higher to lower shells

Limitations of flame test

Qualitative test works only with some metals mixtures of metal also are confusing

Why does each successive period have a reduced electrostatic force?

Because an extra shell is added at each period meaning valence electrons are a greater distance from the nucleus

Steps for atomic absorption spectroscopy

Vaporise, pass through light source, emission spectrum produced

How was court charge calculated?

Number of protons minus number of inner shell electrons

As Core charge increases Why does the atom get smaller?

It pulls the electron shells closer to the nucleus

Ionisation energy

The energy required to remove an electron from its atom in its gas phase

What direction does ionisation energy increase?

Left to right

what direction does ionisation energy decrease?

Down a group

How is core charge affected down a group?

Stays consistent

How is Core charge affected across a period?

It increases

Electronegativity

Ability of an atom to attract electron pairs in a covalent bond towards itself

What reduces the electrons attraction to the nucleus?

Electrons are repelled by the electrons in the inner shells

What happens to the trend in atomic radius down a group?

Increases

Trend in atomic radius across a period

Decreases

First Ionisation energy

Energy required to remove the first valence electron from an atom in the gas phase

Ionisation energy across a period

Increases

Electronegativity Trend down a group

Decreases

Electronegativity trend across a period

Increases

alloys

Materials made by mixing metals with other metals or small quantities of nonmetals

Polymers example

Rubber

Ceramic example

Porcelain

What is a ceramic?

And an organic non-metallic solid formed by a mix of metal and non-metal elements

What are composite materials?

Materials made from two or more different materials

Example of composite material

Fibreglass

Tooth fabrication techniques

Top down bottom up

Top down for fabrication technique

Reduce a larger amount to decide size reached

Bottom up method

Physically building it up atom by atom

What decreases down a row?

Electronegativity first ionisation energy and successive ionisation energy

What increases down a row?

Atomic radius

What increases across a period?

First ionisation energy electronegativity and successive ionisation energy

What decreases across a period?

Atomic radius

Properties of metals

Good conductors of electricity good conductors of heat high melting point in boiling point high density low ionisation energies

Metallic bonding model

3-D lattice of positive cations surrounded by sea of delocalised electrons With strong electrostatic forces

What has nondirectional bonding?

Metallic bonding model

General reaction of metals with acids

Metal + Acid → Salt + Hydrogen gas

Ways to Improve metals

Ally production heat treatment nano structures

Ionic bonding is a bonded between

Metals and nonmetals

Properties of ionic bonding

High melting point in boiling point hard brittle no conduction in solid state, conduct, electricity in liquid aqueous estate

Ionic bonding model

3-D crystal lattice held together by strong electrostatic forces

Why can ionic bonds conduct electricity and liquid or aqueous state?

Breaking of bonds in the lattice to give mobile electrons

What is covalent bonding

Sharing of valence electrons between nonmetals

Covalent molecular bond

Two nonmetals bonded

allotrope

Same atoms different structure, Different physical form

Diamond structure

Covalent network lattice each carbon surrounded by 4 other carbon atoms in a tetrahedral arrangement

Graphite structure

Covalent layer lattice Each carbon bonded to 3 other carbons One Delocalised electron per carbon

What is the allotrope of carbon where the atoms are arranged in a series of pentagons and hexagons?

Fullerenes/ buckyballs

Fullerene structure

Three covalent bonds to each carbon atom so one delocalised electron

Difference between graphene and graphite

graphene is a single layer while graphite is multiple stacked so graphene is stronger because it doesn’t have weak dispersion forces

Nanotube structure

Single layer have hollow structure with walls formed from graphene

Alkanes

Hydrocarbons that contain only single bonds

Hydrocarbon

Compound consisting only of hydrogen and carbon

What is the simplest hydrocarbon

Methane

Formula for methane

CH4

Are forces in alkanes weak or strong

Weak forces between molecules

How does strength of forces increase

As the number of carbon and size of molecule increases

General formula for alkanes

CnH2n+2 where n is number of carbon atoms

Structural isomers

Molecules that have the same chemical formula but different bond arrangements

Parent names for 1 2 3 4 5 6 7 8 9 10

Meth eth prop but pent hex hept oct non dec

What has 1 less hydrogen atom than the corresponding alkane of the same name

Alkyl groups

General formula for alkenes

CnH2n

Are alkenes saturated or unsaturated

Unsaturated so can break bond and attach other atoms

alkenes

Homologous series with at least one double bond

Where do you see if an alkene is cis or trans

Next to the double bond

General formula for benzene

C6H6

Structure of benzene

Ring with alternating single and double bonds

Is benzene stable

Yes

Is benzene saturated or unsaturated

Unsaturated due to double bonds

types of reactions

Substitution, addition, combustion

What type of reaction is it when an alkane reacts with a halogen in the presence of uv Light

Substitution