Basic chemistry

Atomic structure and chemical bonds

Elements in organisms
  • Most common
  • Others
    		•
  • Hydrogen - H
    		•
  • Sodium - Na
    		•
  • Carbon - C
    		•
  • Potassium - K
    		•
  • Nitrogen - N
    		•
  • Iron - Fe
    		•
  • Oxygen - O
    		•
  • Magnesium - Mg
    		•
  • Phosphorus - P
    		•
  • Calcium - Ca
    		•
  • Sulfur - S
    		•
  • Chlorine - Cl

    • Subatomic particles in atoms
    Protons - positively charged, atomic mass = 1 dalton
    Neutron - no charge, atomic mass = 1 dalton
    Electron - negatively charged, atomic mass is negligible

    Characteristics of atoms

    Characteristics of common elements in organisms

    Element

    Atomic Number

    Atomic Weight

    Hydrogen - H

    1

    1

    Carbon - C

    6

    12

    Nitrogen - N

    7

    14

    Oxygen - O

    8

    16

    Phosphorus - P

    15

    30

    Sulfur - S

    16

    32

     

    Electrons are in orbitals in different energy levels

    Isotopes - atoms of an element with different atomic weights

    Element

    Atomic Number

    Atomic Weight

    H

    1

    1

     

    1

    2

     

    1

    3

    C

    6

    12

     

    6

    13

     

    6

    14

    When atoms react, they try to fill their outer electron shell

    Bonds formed between atoms

    Cation - atom which has lost electron(s)

    Anion - atom which has gained electrons

    Ionic bonds - attraction between + and - ions

    Covalent bonds - sharing electrons between atoms

    Covalent bonds -

     

    Polar covalent bonds - unequal sharing of electrons between atoms

    Polar bonds in water molecule

    Hydrogen bonds - weak bonds formed between H (bonded to O or N) and O or N