periodic table and atomic structure

• What is an atom?

  the smallest part of an element
• What is an element?


  A substance made up of only one type of atom
• What are compounds?


  Compounds are two or more elements chemically combined
• How can compounds be separated back into elements?

  by chemical reactions.
• What is a mixture?

  A mixture consists of two or more elements or compounds not chemically combined together
• What happpens to the chemical properties of each substance in a mixture?

  They remain unchanged
• What 5 physical processes seperate mixtures?

  filtration, crystallisation, simple distillation, fractional distillation and chromatography
• What were atoms thought to be before the discovery of the electron?

  tiny spheres that could not be divided
• What did the discovery of the electron lead to?

  the plum pudding model of the atom
• Who discovered the plum pudding model?

  JJ Thomson
• What did the plum pudding model suggest? (3)

  -The atom is a ball of positive charge with negative electrons embedded in it.

  -No empty space.

  -Mass spread throughout
• Who carried out the alpha particle scattering experiment?

  Rutherford
• What did the alpha particle scattering experiment conclude?

  the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged
• What replaced the plum pudding model?

  the nuclear model
• Who created the nuclear model?

  Rutherford
• What was the nuclear model? (3)

  -a positively charged nucleus surrounded by negative electrons

  -mostly empty space

  -mass concentrated at the centre
• How did Niels Bohr adapt the nuclear model?

  By suggesting that electrons orbit the nucleus at specific distances
• What did later experiments after Niels Bohr lead to the idea of?

  protons
• What did James Chadwick provide evidence of?

  the existence of neutrons within the nucleus
• What is the relative charge of a proton?

  +1
• What is the relative charge of a neutron?

  0
• What is the relative charge of a electron?

  -1
• What is the number of electrons equal to in an atom?

  the number of protons in the nucleus
• What is the overall electrical charge of an atom?

  0
• What is the atomic number?

  The number of protons in an atom of an element
• What is the radius of an atom?

  0.1 nm
• What is the radius of a nucleus?

  1/10000
• What is the relative mass of a proton?

  1
• What is the relative mass of a neutron?

  1
• What is the relative mass of a electron?

  Very small or 1/2000
• What is the mass number?

  The sum of the protons and neutrons in an atom
• What is an isotope?

  Atoms of the same element that have different numbers of neutrons
• What is the relative atomic mass of an element

  an average mass that takes account of the abundance of the isotopes of the element.
• How do you calculate the relative atomic mass?

  Ar= total mass of atoms/total number of atoms
• How many electrons can be in the first shell of an atom?

  2
• How many electrons can be in the other shells of an atom?

  8
• What order are the elements in the periodic table arranged in?

  in order of atomic (proton) number
• What are the columns arranged in?

  elements with similar properties, aka groups
• What do elements in the same group in the periodic table have the same number of?

  They have the same number of electrons in their outer shell (outer electrons) and which gives them similar chemical properties
• What were the early periodic tables like?

  They were incomplete and some elements were placed in inappropriate groups