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chemistry rivenshon

Alice Green English

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chemistry rivenshon

History of the structure of the atom
- John dalton (1803)
  - J.J. thomson (1897)
    - Ernest Rutherford (1907)
      - Neils bohr (1913)
        Discovered shells
        Neils Bohr explained that the outer orbit in an atom could hold more electrons than the inner orbit. By knowing this one can determine the atoms chemical properties.
        Niels Bohr adapted Ernest Rutherford's nuclear model. Bohr did calculations that led him to suggest that electrons orbit the nucleus in shells. The shells are at certain distances from the nucleus. The calculations agreed with observations from experiment
      - Discovered that the atom has a nucleus and the orbit
        Ernest Rutherford used a gold foil experiment to discover the modern model of an atom. He concluded that the mass of an atom is concentrated at its centre, the nucleus the nucleus is positively charged with while negative electrons orbited the nucleus.
        gold foil experiment
        They fired atom at a gold foil to see if it bounced off all goes through. They put sensors around the whole thing and discovered some atoms go straight through some collide and change direction and some bounce off each other this is why he proposed that atoms have a solid centre They put centres around the whole thing and discovered some atoms go straight through some collide and change direction and some bounce off each other this is why he proposed that atoms have a solid centre or nucleus
    - discovered the electron
      - J.J. Thomson discovered the electron. He experimented by testing and studying the nature of electric discharge in a high vacuum cathode-ray tube.
        the plum pudding model of the atom. In this model, the atom is a ball of positive charge with negative electrons embedded in it - like currants in a Christmas pudding.
  - Discovered the atom
    - John Dalton thought that all matter was created by atoms, which he believed were indestructible. He also stated that compounds are created by combining two atoms, and that all atoms of an element are identical in their mass and properties
History of the Periodic Table
- John Newlands and Law of Octaves
  - he forward his Law of Octaves in 1864. He arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found a pattern among the early elements. The pattern showed that each element was similar to the element eight places ahead of it.
    - Newlands' table showed a repeating or periodic pattern of properties, but this pattern eventually broke down. By ordering strictly according to atomic mass, Newlands was forced to put some elements into groups which did not match their chemical properties. For example, he put iron (Fe), which is a metal, in the same group as oxygen (O) and sulfur (S), which are two non-metals. As a result, his table was not accepted by other scientists.
- Dmitri Mendeleev
  - Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he did some other things that made his table much more successful. He realised that the physical and chemical properties of elements were related to their atomic mass in a repeating or 'periodic' way, and arranged them so that groups of elements with similar properties fell into vertical columns in his table.
    - Sometimes this method of arranging elements meant there were gaps in his horizontal rows or 'periods'. But instead of seeing this as a problem, Mendeleev thought it simply meant that the elements which belonged in the gaps had not yet been discovered. He was also able to work out the atomic mass of the missing elements, and so predict their properties. And when they were discovered, Mendeleev turned out to be right.
- Why was Mendeleev periodic table excepted by scientist but not Newlands?
  - Both Newland and Mendeleev arranged the elements in order of their relative atomic mass (atomic weight). Both scientists produced tables in which elements with similar properties were placed at regular intervals. Newland kept his table to a strict rule that every eighth element had similar properties (Newlands’ Law Of Octaves). For example this rule made him put oxygen, sulphur and iron in the same property group.
    - However, Mendeleev did some things with his table that made it more useful than Newlands’ table. He predicted that there would be additional elements, as yet undiscovered, and their properties. Because of this he left gaps in his table for these new predicted elements to be added at a later stage. He swapped the order of some elements to suit their properties better and so did not force elements into groups that did not fit or were alike.
      - In conclusion Mendeleev's table became more widely because of his ability to predict characteristics of undiscovered elements and its grouping of elements in the table with similar chemical properties.
- newland was stringed and kept a order but Mendeleev moves and placed them in a pair of Dick periodic way I'm predicted future elements because he's a wizard
- isotopes
  - atoms that have the same number of protons (element), but different numbers of neutrons
Atomic Structure
- An atom has a central nucleus. This is surrounded by electrons arranged in shells.
  - The nucleus is tiny compared to the atom as a whole: the radius of an atom is about 0.1 nm (1 × 10-10 m) the radius of a nucleus (1 × 10-14 m) is less than of the radius of an atom
    - The masses of subatomic particles are very tiny. Instead of writing their actual masses in kilograms, we often use their relative masses.
      - The mass of an electron is very small compared to a proton or a neutron. Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus.
      - Protons and electrons have electrical charges that are equal and opposite.
  - The nuclei of all atoms contain subatomic particles called protons. The nuclei of most atoms also contain neutrons.
Mass and Atomic number
- Atomic number The number of protons in an atom of an element is its atomic number. Remember that: all atoms of a given element have the same number of protons atoms of different elements have different numbers of protons
- number of electrons (-1) = Number of protons (+10
  - An atom contains equal numbers of protons and electrons. Since protons and electrons have equal and opposite charges, this means that atoms are have no overall electrical charge. For example, the atomic number of sodium is 11. Every sodium atom has 11 protons and 11 electrons. It has 11 positive charges and 11 negative charges.
- To calculate the numbers of subatomic particles in an atom, use its atomic number and mass number:
  - number of protons = atomic number
  - number of electrons = atomic number
  - number of neutrons = mass number - atomic number
- The symbol for an atom can be written to show its mass number at the top, and its atomic number at the bottom.
- relative atomic mass:
  - this is the mass of the element that takes into account the relative abundance of isotopes,
    - (mass x abundance) + (mass x abundance) % 100
Isotopes
- Definition: sotopes 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.
  - When the amount of neutral change/mass change of an atom
  - all isotopes are like isosceles triangle because two sides are the same ( protons and electrons0
- Atoms of the same element must have the same number of protons, but they can have different numbers of neutrons. Atoms of the same element with different numbers of neutrons are called isotopes. Isotopes of an element have:
  - the same atomic number
  - different mass numbers
- mass change = isotope
Electron Configuration
- The electronic configuration of an element is related to its position on the periodic table.
  - Number or numbers of circles = Period number
  - Number of electrons in outermost shell = Group number
  - Total number of electrons in all shells = Atomic number
- Electronic configurations and properties of elements: The electronic configurations of atoms help explain the properties of elements and the structure of the periodic table. When atoms collide and react, it is the outer electrons that meet and interact. So, elements in the same group have similar chemical properties because they have the same number of electrons in their outer shell.
Ions
- Atoms into ions
  - A ion is an atom with a CHARGE
metals and non- metals.
- they are opposites
  - Then no metal react with oxygen they become acidec.(PH 1-6)
    - But when a metal reacts with oxygen they become acalides ( HP7-14)
atoms and chemical equations
- ok chidden what do we call the teen tiny particles that all matter is made of ?
  - atoms
  - how may different types of atoms are there in the world
    - about 100
    - what do we call a substance made up of one type of atoms
      - an element
      - how do we shorten the name of elements
        we use symbols
        K. H. O Cl
        what is molecule
        a particle made of 2 or more atoms bonded together
        what is the definition of a chemical compound ?
        s substance made of 2 or more different elements whose atoms are bonded together
        what are the two types of chemical compound
        how do we shorten the name of a compound
        what is do the subscript state symbols S ,L , G and AQ stand for?
        why do we balance
        because the total mass of the mass of the restarts
        the physical state of solid, liquid, gas and aqueous solution
        we use a chemical formula
        Ionic compounds and covalent compound
names of compounds
- if the compound contains only 2 elements its name ends in ide
- if the compound contains only 3 or name element radon of them is oxygen it name ends in ate
seperashon
- filterashon
  - solute and insoluble soils
  - filtration is where you separate a subsets
    - a big soled form a smaller soled
    - a solded from a liquid
      - separating solute and insoluble substances
- chromertogrothy
  - the high the colour up the paper the more disolvent
  - mixture of coloured dyes
  - separating solutions dissolved in the same solvent
- dissolve
  - must you stir in explaining
- distillation
  - you keep da liquid
  - disterlash is the seperashon of two different time of liquids with to diftent boiling pints ( e.g water solfer ). you keep the liquid
  - fractional distillation
    - liquid with similar boiling points
      - separating 2 different liquid based on different boiling points
  - simple distillation
    - liquids with different boiling point
      - separating a liquid from its solvent
- evaperashon
  - salt
    - there longer forming the bigger crystal
- crystallisation
  - removing a liquid leaving a solid behind
chemistry pirodic table
- transition metals
  - • Uses of transition metals
    - The transit transition metals do not react vigourously with water oxygen they will react but much slowly and smaller
      - So they are used as replacements and build with them
  - Compare properties to alkali metals
    - They are much smaller and slower reaction is compare to group 1 alkali
  - • Properties of transition metals
    - transition metals are like the CLASSIC metals
      - and do normal metal things
    - hey are good conductors of heat and electricity. they can be hammered or bent into shape easily. they have high melting points (but mercury is a liquid at room temperature) they are usually hard and tough. they have high densities.
- • Position in the periodic table
- group 7
  - Halogens
    - 4 Why does the reactivity change as you go down the group
      - This is because group 7 elements react by gaining an electron. As you move down the group, the amount of electron shielding increases, meaning that the electron is less attracted to the nucleus.
    - Why are they reactive?
    - Appearance and form, the molecules are diatomic (in pairs)
      - they are like girls there all ways stay in Paris
    - Halogen displacement
      - Halogen displacement reactions are redox reactions because the halogens gain electrons and the halide ions lose electrons.
        When we consider one of the displacement reactions, we can see which element is being oxidised and which is being reduced.
    - • How the reactivity changes down the group
      - thee ferver down the group the less reactive it is
      - farine is the most active
- group 0
  - Noble Gases
    - Properties of noble gases
      - A full outer shell of electrons. ... Because of their full outer shells, they are very inert and stable. ... They are gases under standard conditions. They are colorless and odorless. Their melting and boiling points are close together giving them a very narrow liquid range.
    - Reactivity and why
      - All noble gases have a full outer shell so they do not need to lose all gain electrons
        This is why they did not react and the useless placeholders
      - basically do nothing.
- group 1
  - alkalin metals
    - Why are they reactive?
      - Because I want to have a full shell
    - all group 1 element have I election in there outer shell this means that they have similar properties
    - • Reaction of alkali metals and water
      - o Why does the reactivity change as you go down the group
        Because the gravitational pull on the outside shell is weaker than the more shells or the further down go
      - o How the reactivity changes down the group
        as you go down the group 1 the reactivity is increases
      - o Balanced symbol equation
        2Li(s) + H20 --> 2LiOH(aq) + hz(g)
      - o Word equation
        lithium + water --> lithium hydroxide + hydrogen
      - o Observations
        metal floats. . fizzes. move around turn the universal indicator in the water purple. dissolves. metal less dens than water. makes hydrogen gas react with water to make an alkali