Transcript Document 7508897

Chapter 2
Basic Chemistry
Matter and Energy
Matter – anything that occupies space and has
mass (weight)
• Physical vs Chemical changes
Energy – the ability to do work
• Kinetic
• Potential
• Chemical
• Electrical
• Mechanical
• Radiant
Law of Conservation of Energy- change forms
Composition of Matter
Elements
• Fundamental units of matter
• 96% of the body is made from four elements
• Carbon (C)
• Oxygen (O)
• Hydrogen (H)
• Nitrogen (N)
Atoms
• Building blocks of elements
Atomic Structure
Inside nucleus
• Protons (p+)
• Neutrons (n0)
Outside nucleus in
shells /clouds / or
orbitals
• Electrons (e-)
• Valence e- (outside)
determine chemical
rxns
Identifying Elements
Atomic number
• Equal to the number of
protons that the atoms
contain
Atomic mass number
• Sum of the protons and
neutrons
Atomic Weight and Isotopes
Isotopes – Carbon-12 and Carbon-14
• Have the same number of protons
• Vary in number of neutrons
Atomic weight
• Close to mass number of most abundant
isotope
• Atomic weight reflects natural isotope variation
Radioactivity
Radioisotope
• Heavy isotope
• Tends to be unstable
• Decomposes to more stable
isotope
Radioactivity
• Process of spontaneous atomic
decay
• Alpha, beta, gamma
Molecules and Compounds
Molecule – two or more
like atoms combined
chemically
Compound – two or
more different atoms
combined chemically
Carbon dioxide CO2
Chemical Reactions
• Atoms are united by chemical bonds
• Atoms dissociate from other atoms
when chemical bonds are broken
Electrons and Bonding
• Bonding involves interactions between
electrons in the outer shell (valence
shell)
• Full valence shells do not form bonds
Chemical Bonds
1. Ionic Bonds
• electrons transferred from
one atom to another
• Ions - charged particles
• Anions are negative (Cl-)
• Cations are positive (Na+)
Chemical Bonds
2. Covalent Bonds
• Electrons are shared
• Single covalent bonds share one electron
• Double covalent bonds share two electrons
Examples of Covalent Bonds
Polarity
Polar covalent bonds
• e- shared equally
• No charge; neutral
Non-polar covalent bonds
• e- shared unequally
• Results in positive and
negative sides
• Have you bent water?
Carbon bonds
Covalent bonds between
two carbon atoms
• Single bonds
• Double bonds
• Triple bonds
• Quadruple bonds
Important for organic compds
Chemical Bonds
3. Hydrogen bonds
• Weak chemical bonds
• Hydrogen is attracted to
negative portion of polar
molecule
• Provides attraction
between molecules
Patterns of Chemical Reactions
1. Synthesis reaction (A+BAB)
• Atoms or molecules combine
• Energy is absorbed for bond formation
• Also called anabolic
2. Decomposition reaction (ABA+B)
• Molecule is broken down
• Chemical energy is released
• Also called catabolic
Synthesis & Decomposition Reactions
3. Exchange reaction
• (AB + C AC+B) single
• (AB+CD  AD+CB) double
• Involves both synthesis and decomposition
reactions
• Switch is made between molecule parts
and different molecules are made
Ex. Neutralization – acid/base reaction