Transcript Chapter 2 Chemistry - Fort Thomas Independent Schools

Chapter 2 Chemistry
Chemistry
• Matter  anything that has mass & takes
up space
• Mass  amount of matter an object has
• Elements  pure substances that cannot
be broken down into simpler
kinds of matter
• Important elements : C, O, H, N
Chemistry
• Atom  simplest particle of an element
•
 the properties of an atom
determine the properties of
that matter
Nucleus  core of an atom ; protons &
neutrons
1. Protons  + charge , mass 1 amu
2. Electrons  - charge, no mass
3. Neutrons
 no charge, mass 1 amu
Electrons  outside the nucleus on shells
2 on the first & 8 on the rest
Periodic Table
• Arranged in increasing atomic #
• Atomic # = number of protons
• # of Protons = number of electrons
• Atomic mass = # of protons + # of
neutrons
• Each column has the same number of
outside ( valence electrons)
Chemistry
• Compound  pure substance of 2 or more
elements combined
H2O, CH4, (NH4)2SO4
•
Bonds
Bonds  attachments of atoms
in a compound
1. Covalent  electrons shared
2. Ionic  1 atom gains electrons
& 1 atom loses
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Chemistry
• Molecule  simplest part of a substance
•
that has all the properties of
that substance and can exist
by itself
 can be two atoms of the same
element or more than one
type of element
Ex: O2, N2, C6H12O6
Chemistry
• Reaction  two substances interact &
change identity
Reactants ------ Products
H2 + O2 → 2H2O
↔ Means that the reaction can go
both ways
Chemistry
• Exothermic reactions that release heat/
energy
• Endothermic  reactions that absorb
heat/energy
• Activation energy  energy needed to
start a reaction
Chemistry
• Catalyst  speed up reactions by lowering
activation energy
• Enzymes  are biological catalysts
• Substrate
substance that binds to
enzymes
Enzymes
Functions
• Are substrate specific
• Lock & key fit
• Speed up reactions by
lowering activation
energy
Chemistry
• Solutions  are mixture where one
substance is dissolved in
another
• Solute  substance that gets dissolved
Ex: Kool Aid Powder
• Solvent  does the dissolving
Ex: Water – water is the universal
solvent
Chemistry
• Concentration  amount of solute per amount
•
•
of solution
 tells us how spread out the
particles are
Saturated  no more solute can be added
 it has the maximum amount of solute
Aqueous  something is dissolved in water
(aq)
Chemistry
• Dissociation of water
H2O ↔ H+ + OHhydrogen ion + hydroxide ion
• Ions  are any particle that has a charge
Chemistry
• ACIDS & BASES
• Acids  form hydrogen ions in solution (H+ )
•
 have a sour taste
Ex: HCl  H+ + ClBases  form hydroxide ions in solution (OH-)
 have a bitter taste
Ex: NaOH  Na+ + OH –
Chemistry
• pH Scale  measures the concentration of
•
hydrogen ions in solution
 Range is 0-14
 0 – 7 is an acid
 7- 14 is basic (alkaline)
→ 7 is neutral (water)
Buffer  substances that neutralize a
small amount of acid or base.
 maintain the pH within our bodies.