Atomic structure

• What happens when an atom gains or loses electrons?

  It becomes an ion
• What is a negative ion?

  An atom with more electrons than protons
• How is a one minus negative ion formed?

  By adding one extra electron
• What is a positive ion?

  An atom with more protons than electrons
• How is a one plus positive ion formed?

  By losing one electron
• What does the atomic number indicate?

  How many protons an atom has
• What are the differences between atoms and ions?

  • Atoms have balanced charges
  • Ions have unbalanced charges
  • Ions can be positive or negative
• How do you calculate the number of neutrons in an atom?

  • Subtract atomic number from mass number
• What determines which element an atom is?

  The number of protons in the nucleus
• What is the atomic number?

  Number of protons in an atom
• What is the process to calculate the relative atomic mass of an element?

  1. Multiply each isotope's abundance by its mass.
  2. Sum these values.
  3. Divide by the total abundance of isotopes.
• What are the differences between isotopes of the same element?

  • Same number of protons
  • Different number of neutrons
  • Different mass numbers
• Which elements are included in the alkali metals?

  Lithium, sodium, potassium, rubidium, cesium, francium
• Why are alkali metals so reactive?

  They easily lose their one outer electron
• What does the term reactivity refer to?

  How easily atoms lose or gain electrons
• What type of compounds do alkali metals typically form with non-metals?

  Ionic compounds
• What are the general properties and trends of alkali metals?

  • Soft with low densities and melting points
  • More reactive than other metals
  • Reactivity increases down the group
  • Melting and boiling points decrease down the group
• How do alkali metals react with water, chlorine, and oxygen? why are they stored in oil?

  • React with water to form metal hydroxide and hydrogen
  • React with chlorine to form white metal chloride salts
  • React with oxygen to form metal oxides
  • they are stored in oil because the react very vigorously with oxygen and water, including moisture in the air
• What is the general trend in reactivity and atomic structure of alkali metals?

  • Reactivity increases down the group
  • Atoms get larger, outer electron further from nucleus
  • Easier to lose outer electron, increasing reactivity
• What are the types of oxides formed by alkali metals when reacting with oxygen?

  • Lithium: lithium oxide ($Li_2O$)
  • Sodium: sodium oxide ($Na_2O$) or sodium peroxide ($Na_2O_2$)
  • Potassium: potassium peroxide ($K_2O_2$) or potassium superoxide ($KO_2$)
• What is the process of filtration?


  separates mixtures of insoluble solids and liquids.

  pour the mixture through filter paper and filter funnel.

  The insoluble solid will be trapped, the liquid runs through the paper and is collected in the funnel
• what is the process of crystallisation?


  separates solutions into their constituent: dissolved solids and

  liquids

  1. heat the mixture so that the solvent evaporates
  2. once crystals of the solute form, stop heating the mixture
  3. leave it in a cool place to dry
  4. we can collect the solvent by condensing it as it evaporates
• What is the process of chromatography?


  Separates solutions with a number of different solutes in the solvent

  1. Place a drop of the solution to be separated near the bottom of a piece of chromatography paper
  2. Dip the very bottom of the paper into a suitable solvent
  3. The solvent moves up the paper and carries the solutes in the solution with it
  4. Different solutes move at different speeds, so they separate on the paper
• what is the process of simple distillation?

  separates 2 liquids with different boiling points.

  1. mixture is heated until the liquid with the lower boiling point starts to boil
  2. the vapour released passes through a condenser, where the gas cools back into a liquid
• What is the process of fractional distillation?


  Separates lots of liquids with different boiling points

  1. the mixture is slowly heated until the liquid with the lowest boiling point boils and then condenses
  2. Then we increase temperature slowly to collect the other fractions
• what was Thomsons plum pudding model?


  in 1898, j.j Thomson discovered electrons

  he believed that atoms contained tiny, negative electrons surrounded by a sea of positive charge.
• what was Rutherfords nuclear model?


  Geiger and Marsden carried out an experiment in which they bombarded a thin sheet of gold with alpha particles. Most of the positively charged alpha particles passes straight through the atoms and a tiny number were deflected back.

  Rutherford looked at these results and concluded that the positive charge in an atom must be concentrated in a very small area. This area was called the nucleus which contained positively charged particles called protons and the resulting model became known as the nuclear model of the atom.
• what was Bohr ‘modern model’?


  he discovered that the electrons orbit the nucleus at fixed distances

  later experiments showed that the nucleus is made out of protons and neutrons
• what did James Chadwick discover?


  in 1932, he discovered that some particles in the nucleus have no charge at all called neutrons
• what is the relative mass of proton, neutrons and electron?


  Proton: 1 Neutron: 1 Electron: ~0.0005
• What was John Newlands periodic table?


  In 1864, he was the first chemist to devise a periodic table. However, the table was incomplete and some elements were placed in inappropriate groups as he arranged elements in order of atomic weight
• what was Mendeleev’s periodic table?


  he realised that some elements were not discovered yet. Therefore, In 1869, he created his table and left gaps and also reordered some elements. Each element were placed in groups with elements that had similar properties. He Used his periodic table to predict the existence and properties of new elements. When subatomic particles were discovered, it revealed that Mendeleev had organised the elements in order of increasing atomic number(n.o of proton)
• What are isotopes?


  Isotopes are different forms of the same element, that have the same number of protons, but a different number of neutrons
• What is the equation to find the number of neutron?


  neutrons=atomic number- mass number
• what is a molecule?

  2 or more atoms that a chemically bonded
• What are some physical properties of metals?

  • Metallic bonding
  • Malleable
  • Good conductors of electricity
  • High melting and boiling points
  • Shiny
  • Sonorous
• What are some properties of non-metal?


  Brittle, poor conductors of heat and electricity, low melting and boiling points, dull in colour
• what are transition metals?


  Elements in the middle of the periodic table that can form more than one ion. they also make good catalysts
• what is a catalyst?


  A substance that increases the rate of a chemical reaction without being consumed in the process.
• What are the colours of the water for bromine, chlorine, and iodine?


  Bromine water is orange

  Chlorine water is colourless

  Iodine water is brown