C1 Atomic Structure and the Periodic Table Flashcards
How many elements are there
There are 118 different types of elements that humans have discovered and each one has its own chemical symbol
What are atoms
Atoms are the smallest possible unit of an element
What are compounds
Molecules made up of the atoms of at least 2 different elements
Compounds have formulae that are made by combining the chemical symbols of the elements that combine to make them
What happens in a chemical reaction
Compounds are broken up or formed
New substances are created
Energy change
No atoms are created or destroyed
What is a chemical equation
A written representation of a chemical reaction
What are reactants
Chemicals that are reacting with each other are called the reactants
Reactants are found on the left of equations
What are products
Chemicals that are being made are called the products
Products are found on the right of equations
What is a word equation
A chemical reaction expressed in words rather than chemical formulae
Word equations state the reactants, products, and direction of the reaction in a form that could be used to write a chemical equation
What is a symbol equation
A symbolic representation of a chemical reaction
Symbol equations state the reactants, products, and direction of the reaction
Symbol equations must be balanced
What are mixtures
Mixtures are made of 2+ substances (elements or compounds) that haven’t been combined chemically
Mixtures can be separated
Their chemical properties don’t change because they have been mixed with another substance
What are separation techniques
A physical process used to separate mixtures and compounds into the elements or compounds that make them up
What is crystallisation
A separation technique for separating solutions into solutes and solvents
What is filtration
A separation technique for separating mixtures that contain insoluble solids and liquids
Performed by passing the mixture through filtration paper
The insoluble solid is trapped by the filter paper
The liquid runs through the filter paper and is collected
What is chromatography
A separation technique for separating multiple solutes from a solvent
What is distillation
A separation technique used to separate a mixture of liquids
Uses the liquids’ different boiling points to separate them
What is simple distillation
A separation technique for separate two liquids with different boiling points
What is fractional distillation
A separation technique used to separate multiple liquids with different boiling points
What is Dalton’s model of the atom
John Dalton proposed an atomic model often referred to as the Billiard Ball Model
He defined an atom to be a ball-like structure, as the concepts of atomic nucleus and electrons were unknown at the time
What is Thomson’s model of the atom
English physicist called J. J. Thomson discovered electrons
Thomson modelled the atom as a ‘plum pudding’: a ball of positive charge (dough), with negatively charged electrons (currants in the pudding) mixed in with the ‘dough’
What is Rutherford’s model of the atom
Ernest Rutherford discovered that alpha particles could bounce back off atoms
Rutherford concluded that an atom’s mass is concentrated in the atom’s centre.
This was called the “nucleus” and it contained positively charged particles called protons
Referred to as the nuclear model
What is Bohr’s model of the atom
Niels Bohr discovered that electrons orbit the nucleus at fixed distances
What is the relative charge of a proton
+1
What is the relative charge of electrons
-1
What is the relative charge of neutrons
0
How is relative mass calculated
Number of protons + number of neutrons
What size are atoms
The radius of an atom is approximately 0.1 nanometres
The nucleus of an atom is 10,000 times smaller than the atom
What are isotopes
Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number
All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom
What is protium
Protium is a hydrogen atom with 1 proton and no neutrons
99.98% of hydrogen atoms are protium
Used in fuel cells and the production of plastic
What is deuterium
Deuterium is a hydrogen atom with 1 proton and 1 neutron
0.02% of hydrogen atoms are deuterium
Used in nuclear fusion
What is tritium
Tritium is a hydrogen atom with 1 proton and 2 neutrons
Very rare
Used in thermonuclear fusion weapons
What is relative atomic mass
Average mass of all the isotopes of an element
Takes into account isotope abundance
What is electron structure
Electrons have fixed positions in atoms called shells or energy levels
Shells go around the atom’s nucleus
What are electron shells
Electrons fill an atom’s shells in order of increasing energy
The closer a shell is to the nucleus, the lower its energy level, so the first shell that is filled is the closest to the nucleus
What is electron configuration
Electron configuration tells us how an atom’s electrons are organised
The inner shell can have a maximum of 2 electrons and the next two shells can have a maximum of 8 electrons
Extra electrons are then put into a fourth shell and so on