Chem chp 3/4

• How is periodic table arranged

  increasing atomic number(protons)
• Formula for isotopes


  % of isotope A x mass of isotope A + % of isotope B x mass of isotope B/ 100
• Atomic number is


  number of protons
• number of neutrons

  atomic mass - atomic number
• Why will an atom be neutral


  Same number of protons and electrons
• number of protons

  Mass number - number of neutrons
• label atomic structure

  
• Isotopes

  Atoms with the same number of protons but different numbers of neutrons
• Size and charge of electron

  -1 and relative atomic mass 1/1840
• Size and charge of a neutron

  0 and relative atomic mass 1
• Size and charge of a proton

  +1 and relative mass is 1
• atomic mass


  Number of protons and neutrons
• Relative atomic mass(Ar)

  The average mass of all the isotopes of an element
• atomic number


  the number of protons in the nucleus of an atom
• Molecule


  A group two or more atoms chemically bonded together.
• Atom


  Smallest particle of an element that consists of electrons surrounding the nucleus that contains protons and neutrons
• noble gases

  Full outer shell, so unreactive, all non metals, colorless and non flammable gases
• Non-metal properties


  4-7 outer shell, covalent, poor conductors, acidic oxides, don't react with acids, brittle and low mp
• Metal properties

  1-3 outer shell, metallic, good conductors, basic oxide, react with acids and malleable and can be bent
• Electronic configuration of first 20 elements

  2.8.8
• Electronic configuration reality

  Further away the electron is from the nucleus the more energy the shell has the less reactive
• What does Period represent in electronic configuration

  No. of shells an atom has
• What does group represent in electronic configuration

  Shows valence electrons each atom has
• The horizontal rows on the periodic table are called


  Period
• The vertical columns on the periodic table are called

  Groups
• How are elements arranged on the periodic table?

  in order of increasing atomic number(proton)