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Chemistry Topic 1 (Topic 1 Atomic Structure (Atomic Structure (Subatomic…

- - - - An atom chemically combined with other elements to make a compound
    - - There are 118 different types of elements that humans have discovered. Each has its own symbol
    - - The smallest piece of an element that can exist
  - - - A chemical equation shows what happens in a chemical reaction using symbols or words. The reactants (the chemicals that are reacting) are on the left-hand side, and the products (the chemicals that are forming) are on the right-hand side.
      - Word equations
        
        Using the words instead of symbols
      - Symbol equations
        
        Symbol equations must be 'balanced' (have the same number of atoms of each element on each side of the equation). This is because atoms aren't created or destroyed during chemical reactions.
  - - - Fractional Distillation
        
        eparates lots of liquids with different boiling points.
        
        The mixture is slowly heated until the liquid with the lowest boiling point boils and then condenses.
        
        Then we increase temperature slowly to collect (boil then condense) the other fractions.
      - Simple Distillation
        
        The mixture is heated until the liquid with the lower boiling point starts to boil.
        
        The vapour released passes through a condenser, where the gas cools back into a liquid.
        
        Separates 2 liquids with different boiling points.
      - Filtration
        
        The mixture is poured into a flask
        
        The liquids collects in the flask and the solid is left in the filter paper
        
        A piece of filter paper is put into a funnel
      - Chromatography
        
        A spot of solution to be separated is placed near the bottom of a piece of chromatography paper.
        
        The paper is held upright. The bottom of the paper is dipped into a suitable solvent .
        
        As the solvent soaks up the paper, it carries the solutes in the spot with it. The different solutes (solids) in the spot of solution move at different speeds.
        
        This leaves a pattern of the separate solutes on the chromatography paper.
      - Crystallisation
        
        Separates solutions into their constituent (different) parts: dissolved solids (solutes) and liquids (solvents).
        
        Heat the mixture so that the solvent evaporates.
        
        Eventually, crystals of the solute (dissolved solids) will form.
        
        We can collect the solvent (liquid) by condensing it as it evaporates.
    - - Solvent
        
        The liquid in which a solid dissolves.
      - Solute
        
        Dissolved solid.
      - Solution
        
        A liquid that contains a dissolved solid.
  - - - Proton
        
        Charge of 1
      - Neutron
        
        Charge of 0
      - Electron
        
        Charge of -1
      - An atom consists of electrons orbiting a central nucleus. The radius of the nucleus is about 10,000 times smaller than the radius of the atom, but almost all the atom's mass is concentrated in the nucleus.
      - An atom consists of electrons orbiting a central nucleus. The radius of the nucleus is about 10,000 times smaller than the radius of the atom, but almost all the atom's mass is concentrated in the nucleus.
    - - Atomic Number
        
        The number of protons in a carbon atom.
      - Mass Number
        
        The relative mass of a carbon atom.
  - - - Deuterium
        
        Deuterium is a hydrogen atom with 1 proton and 1 neutron. Around 0.02% of hydrogen atoms are deuterium.
      - Tritium
        
        Tritium is a hydrogen atom with 1 proton and 2 neutrons. It is very rare.
      - Protium
        
        Protium is a hydrogen atom with 1 proton and 0 neutrons. 99.98% of hydrogen atoms are protium.
    - - Isotope Abundance
        
        The isotope abundance tells us how often each different isotope of an element is found.
      - Calculating
        
        The relative atomic mass (Ar) is the average mass of all of the isotopes of an element. It takes into account how often each isotope is found (the isotope abundance).
        
        The relative atomic mass (Ar) is the average mass of all of the isotopes of an element. It takes into account how often each isotope is found (the isotope abundance).
    - - Isotopes
        
        Atoms of the same element that have different numbers of neutrons.
      - Filling 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, so the first shell that is filled is the closest to the nucleus.
      - Electron Configuration
        
        Electron configuration tells us how an atom's electrons are organised.
        
        The inner shell (closest to the nucleus) can have a maximum of 2 electrons and the next two shells can have a maximum of 8 electrons.
        
        Any extra electrons are then put into a fourth shell.
  - - - Newland
        
        John Newlands was the first chemist to devise a periodic table.
        
        His periodic table was ordered by the mass of the element.
        
        However, the table was incomplete, and some elements were placed in inappropriate groups.
      - Mendeleev
        
        Dimitri Mendeleev realised that there may be undiscovered elements.
        
        He added gaps to Newlands’ table to account for undiscovered elements.
        
        He even predicted the properties and masses of these undiscovered elements!
      - Current Table
        
        The discovery of protons and isotopes has shown that Mendeleev ordered elements exactly by atomic number (number of protons).
        Therefore, the modern periodic table looks very similar to Mendeleev's (except the gaps are filled).
    - - The metals are found on the left side of the periodic table because they have few electrons in their outer electron shell.
      - Periods
        
        The table is ‘periodic’ because elements with similar properties occur at regular intervals, i.e. periodically.
        Therefore, the rows of the periodic table are called periods.
      - Groups
        
        Elements in the same column have the same number of electrons in their outer shell (the highest energy level).
        Columns are called groups, and the group number equals the number of electrons an atom of that element has in its outer shell.
      - Predicting Trends
        
        Because all elements in a column have the same number of electrons in their outer shell, they have similar chemical properties.
        This means they will all react in similar ways.
    - - Metals
        
        Where they are found
        
        Metals are found on the left of the periodic table because they have few electrons in their outer shell.
        When metals react, they lose 1 or more of these negatively charged electrons to form positively charged ions.
        
        Properties
        
        High melting and boiling points.
        
        Good conductors of heat and electricity.
        
        They are all solids (except for mercury) at room temperature.
      - Non Metals
        
        Where they are found
        
        Non-metals are found on the right of the periodic table because they have many electrons in their outer shell.
        
        When non-metals react, they either:
        
        Gain electrons to form negatively charged ions.
        
        Or share electrons to form neutral molecules.
        
        Properties
        
        Lower melting and boiling points.
        
        Often found as gases.
        
        Generally do not conduct heat or electricity.
      - Noble Gasses
        
        Properties
        
        Inert
        
        The elements in group 0 are unreactive because they have a full outer shell of electrons. They do not gain or lose electrons to fill up this shell as it is already full.
        They can be used in light bulbs because the noble gases will not react with the hot metal filament.
        
        Monotonic
        
        Because noble gases are unreactive, they exist as single atoms (monatomic) instead of forming molecules.
        
        Low Boiling Point
        
        The noble gases have low boiling points.
        But their boiling points do increase as you move down the periodic table. This is because the relative atomic mass increases lower down the periodic table.
        
        Low Density
        
        The noble gases (in group 0) have low densities.
        
        Their densities do increase as you move down the periodic table because of their increasing relative atomic mass.
        
        This low density makes them useful in balloons.
        
        Halogens
        
        Elements in group 7 in the periodic table are called halogens. They have 7 electrons in their outer shell. They are very reactive because they easily accept an electron into this outer shell. They have similar properties and react in similar ways.
        
        Structure
        
        Halogens are in group 7 and so have 7 electrons in their outer shell.
        
        When they react, they gain 1 electron to get a full outer shell.
        
        By gaining 1 electron, they form a negative ion.
        
        In their elemental form, halogens share electrons to make diatomic molecules (molecules made of pairs of atoms).
        
        When a metal atom transfers its outer electron to a non-metal atom (like a group 7 atom), salts are formed.
        The result is a compound where all the ions have a full outer shell.
        
        Trend
        
        As you go down the group, the halogens become less reactive. This is because:
        
        The atoms gain more electron shells.
        
        The outer electron shell is further from the nucleus.
        
        The attraction between the nucleus and the electron (to be gained from another element) decreases.
      - Alkali Metals
        
        Where they are found
        
        The elements in group 1, found on the far left of the periodic table, are called the alkali metals.
        
        Trends
        
        The number of electron shells increases meaning there is a greater distance between the outer electron and the nucleus.
        
        As you move down group 1 of the periodic table, the reactions of alkali metals become quicker and more vigorous. This is because:
        
        The greater the distance between the outer electron and the nucleus, the weaker the attraction between them.
      - Transition Metals
        
        Properties
        
        Low Reactivity
        
        Greater strength and hardness
        
        Higher melting Points
        
        High density
        
        Can form different colour compounds
        
        Often used as catalysts