Introduction to Chemistry

1
Introduction to Chemistry Background for
Nanoscience and Nanotechnology

• Prof. Petr Vanysek

2
Introduction to ChemistryCompounds
3
(No Transcript)
4
(No Transcript)
5
Chemical Bonding

• Covalent bonds
• Ionic bonds
• Metal bonding

6
Covalent bonds

• Covalent bonding is when electrons are shared
  between to atoms or more.
• The number of covalent bonds an atom is likely to
  form is determined by its place in the periodic
  table and the number of valence electrons it has.
• An atom will share electrons with another atom so
  that it results in them both having a full
  valence shell. Usually this will be 8 electrons.

7
Ionic bonds

• When a metal and a non-metal form bonds they are
  typically ionic bonds where electrons are
  transferred from the metal to the non-metal.
• Some metals will lose enough electrons to achieve
  a complete valence shell.
• Non-metals will usually gain enough electrons to
  achieve a complete valence shell.
• Many metals are able to form ions with more than
  one charge.

8
Metal bonding

• In metals the atoms are held together by metal
  bonding. Electrons can easily transfer from one
  atom to the next. This suggests a model of
  positive ions in a sea of electrons. Metals can
  conduct electricity because electrons flow easily
  in any direction.

9
Covalent and Ionic Bonding
Atom of Covalent Bonds Typical charge for an Ion
H 1 1
C 4
O 2 -2
N 3
F, Cl, Br, I 1 -1
S 2 -2
Si 4
Li, Na, K 1
Be, Mg, Ca, Sr, Ba 2
10
Polar Molecules

• Polar Molecules
• If the electron density is not distributed evenly
  around a molecule then they are polar.

11
Intermolecular BondingBonding between
moleculesvan der Waals forces

• Hydrogen bonding
• This relatively strong type of inter-molecular
  bonding which typically occurs between a hydrogen
  atom of one molecule and an electron pair or
  electronegative atom of another molecule.
• Multiple hydrogen bonds hold the DNA double helix
  together.
• Dipole interaction
• London forces
• These are induced forces caused by a temporary
  rearrangement of the electron clouds when
  molecules bump together.

12
Hydrogen Bonding


-
-
H
13
Hydrogen Bonding
14
Dipole Interaction

• http//www.chemguide.co.uk/atoms/bonding/vdw.html
• The partial positive and negative ends of the
  molecules hold the molecules together.

15
London Forces
London forces are induced dipoles caused by
temporary rearrangement of the electron cloud.
Two hexane molecules approach.
The hexane molecules bump into each other.
The electron clouds rearrange to form a temporary
dipole.
-
-
-



-
-
-



16
Polymers

• Polymers are large chainlike molecules that are
  built from smaller molecules called monomers.
• For example polyethylene is formed from ethylene
• Proteins are natural polymers.
• http//www.pslc.ws/macrog.htm

17
Chemical Reactions

• Involve the making or breaking of chemical bonds.
• Chemical reactions result in making a new
  substance with different properties from the
  original substance.

18
Structure of Materials
19
Biological Organization
Organelles
Proteins
Nucleic Acids
Membranes
20
(No Transcript)
21
(No Transcript)
22
Review of Chemistry

• States of Matter
• Atoms, Molecules and Ions
• Subatomic particles
• Periodic Table
• Covalent and ionic bonding
• Chemical reactions
• Intra-molecular forces
• Polymers