MODULE

• Chemistry


  is the study of matter and the changes it undergoes
• Matter


  is anything that occupies space and has mass
• Substance


  is a form of matter that has a definite composition and distinct properties
• Mixture


  is a combination of two or more substances in which the substances retain their distinct identities
• Homogeneous mixture


  composition of the mixture is the same throughout eg. soft drink, solder
• Heterogeneous mixture


  composition is not uniform throughout eg. iron filings in sand Milk
• Physical means


  can be used to separate a mixture into its pure components
• Element


  a substance that cannot be separated into simpler substances by chemical means
• 118 elements have been identified

  82 elements occur naturally on Earth eg. gold, aluminum, lead, oxygen, carbon, sulfur

  36 elements have been created by scientists eg. technetium, americium, seaborgium
• Compound


  is a substance composed of atoms of two or more elements chemically united in fixed proportions
• Compounds can only be separated into their pure components (elements) by chemical means
• Molecule


  is an aggregate of two or more atoms in a definite arrangement held together by chemical forces
• Diatomic molecule


  contains only two atoms eg H2, N2, O2, Br2, HCl, CO
• Polyatomic molecule


  contains more than two atoms eg O3, H2O, NH3, CH4
• Ion 


  is an atom, or group of atoms, that has a net positive or negative charge
• Cation


  Ion with a positive charge

  If a neutral atom loses one or more electrons

  it becomes a cation
• Anion


  Ion with a negative charge

  If a neutral atom gains one or more electrons

  it becomes an anion
• Monatomic ion


  contains only one atom eg Na+, Cl- , Ca2+, O2- , Al3+, N3-
• Polyatomic ion


  contains more than one atom eg. OH- , CN- , NH4 +, NO3 -
• Ionic compounds


  consist of a combination of cations and an anions
• Chemical Bonds


  net forces of attraction that hold atoms together
• Covalent Bond


  sharing of e-

  atoms of non-metals combine

  electronegativity difference is 0 to < 2
• Electronegativity


  is the ability of an atom to attract toward itself the electrons in a chemical bond
• Ionic Bond


  attraction between cations and anions

  atoms of metal and nonmetal combine

  metals lose e- (cations), nonmetals gain e- (anions)
• Valence electrons


  are the outer shell electrons of an atom. The valence electrons are the electrons that participate in chemical bonding
• Lewis Dot Symbol


  Consists of the symbol of an element and 1 dot for each valence e- in an atom of the element
• Octet Rule


  Observed tendency of atoms (representative elements) to lose , gain or share e- in order to acquire an octet e- in their outermost main energy level
• Valence Shell Electron Pair Repulsion Theory (VSEPR)


  Determines the shape of the molecule
• Polar


  unequal distribution

  different elements

  non-metal
• Non-polar


  equal distribution

  same elements

  non-metal
• Intermolecular Forces of Attraction (IMFA)


  Attractive forces between molecules
• Dipole-dipole forces


  between polar (covalent) molecules

  greater than 0.5 en

  opposite attracts
• Ion-dipole forces


  attraction between an ion (cation or anion) and a polar molecule
• London dispersion forces


  Van der Waals interaction

  attractive forces in all (covalent) molecules
• Ion-ion forces


  Electrostatic forces

  Attractive forces between cations and anions in ionic compounds
• Hydrogen bond


  special type of dipole-dipole interaction between the H atom in a polar bond and an electronegative O, N or F atom
• Self-assembly


  The self-organization of components into patterns of structures without human intervention due to different kinds of interactions happening among the components
• Molecular self-assembly


  involves the Van der Waals interaction, electrostatic, hydrophobic, hydrogen bonds, and coordination bonds
• Macroscopic objects


  involves gravitational interaction, external electromagnetic field, capillary, and entropic interaction
• Static self-assembly


  System that are at local equilibrium and do not dissipate energy

  Requires energy to happen