Upload
martina-green
View
215
Download
0
Tags:
Embed Size (px)
Citation preview
The Chemistry of Life
Section 2.1
Atoms
• The basic unit of matter are atoms.
• 100 million atoms would make a row only about 1 cm long!
• Consists of subatomic particles:
- Protons
- Neutrons
- Electrons
Subatomic particles
• Protons- positively charged.
• Neutron- has no charge.
- They form the nucleus of the atom.
• Electrons- negatively charged with 1/1840 the mass of a proton.
- In constant motion in space around the nucleus.
Elements
• A chemical element is a pure substance that consists entirely of one type of atom.
Can you name some?
• The number of protons in an atom of an element is the element’s atomic number.
- Carbon: atomic number 6
- Has 6 protons and 6 electrons
Isotopes
• Atoms of the same element that differ in amount of neutrons.
- Sum of protons and neutrons in nucleus is the mass number.
Chemical Compounds
• A substance formed by the chemical combination of two or more elements.
- Water: H2O, 2 molecules of hydrogen
1 molecule of oxygen
Chemical Bonds
• An ionic bond is formed when one or more electrons are transferred from one atom to another.
- An atom that loses electrons = positive
- An atom that gains electrons = negative
• Example: Table Salt, NaCl
Chemical Bonds
• A covalent bond forms when electrons are shared between atoms.
- Example: Water, H2O
Section 2.2
2.2-Water
• A water molecule, H2O, is neutral.
• It is polar.
• Water molecules are held together by hydrogen bonds.
Hydrogen bonds
• Cohesion is an attraction between molecules of the same substance.
• Adhesion is an attraction between molecules of different substances.
Solutions and Suspensions• A solution is an even mix of components.
- A solute is the substance that is dissolved (salt)
- A solvent is the substance in which the solute dissolves (water)
• A suspension is a mixture of water and non-dissolved material
Example- blood
pH scale
• Ranges from 0-14.
• Solutions with a pH below 7 are acidic.
• Solutions with a pH above 7 are basic.
Section 2.4
2.4-Chemical Reactions
• A process that changes one set of chemical reactions.
- Reactants: elements that enter into a reaction.
- Products: elements that are produced by a chemical reaction.
H2 + O H2O
Activation energy
• The energy to get a reaction started.
• It is a factor in whether the overall chemical reaction releases energy or absorbs energy.
Enzymes
• A catalyst is a substance that speeds up the rate of a chemical reaction.
• Enzymes are proteins that act as biological catalysts; speed up reactions in cells.