The Chemistry of Life –
Matter and Energy
Chapter 2
The Nature of Matter
 Atoms



Basic unit of matter
Incredibly small (you could line up 100 million
acros the width of your little finger)
Made of three particles
• Protons – positive charge, located in nucleus
• Neutrons – no charge, located in nucleus
• Electrons – negative charge, located around
nucleus

Usually electrically neutral (protons=electrons)
The Nature of Matter

Elements and Isotopes

Element – pure substance, only one type of atom
• Atomic number – number of protons in nucleus

Isotope – atoms of the same element that have
different numbers of neutrons
• Mass number – number of protons and neutrons in nucleus
• All isotopes of an element have the same chemical
properties
• Radioactive isotopes – nuclei are unstable and breakdown

Used for geologic dating, cancer treatment, protection from
bacterial outbreak in food etc
The Nature of Matter
 Chemical

Compounds
A substance formed by chemical combination
of two or more elements
• Physical and chemical properties are different from
the elements it is made of
The Nature of Matter
 Chemical


bonds
Created by interaction between electrons
Two major types
• Ionic – occur when electrons are transferred,
causes an electrically charged atom (ion)
• Covalent – occurs when electrons are shared

Creates a molecule
Properties of Water
 The



Water Molecule
Found in an liquid state all over the planet
Polarity – unequal attraction between the
shared electrons
Hydrogen bonding – attraction between
molecules because of polarity
• cohesion
• Adhesion
• Heat capacity
Properties of Water
 Solutions


and Suspensions
Mixture – physically mixed but NOT
chemically combined
Solution – mixture where things are evenly
distributed
• Solute – substance that is dissolved
• Solvent – substance in which solute dissolves

Suspensions – mixture of water and
nondissolved material
Properties of Water
 Acids,

Bases and pH
pH scale – measures concentration of H+
(hydrogen ion) in solution
• Ranges from 0 to 14




7 – neutral
Lower values – acidic
High values – basic
Buffers – weak acids or bases that prevent
sharp, sudden changes
Carbon Compounds
 The



Chemistry of Carbon
Carbon atoms have 4 valence electrons
(outermost – needed for reactions)
Allows them to bond with many different
elements
Allows it to bond to itself to create long chains
Carbon Compounds
 Macromolecules



Large molecules
Created when monomers (single units) form
polymers (multi-units)
Four major types
Carbon Compounds
 Carbohydrates





Made of carbon, hydrogen and oxygen
Main source of energy for living things
Can be used for structural purposes
Simple sugars – monosaccharides (glucose)
Complex – polysaccharides (glycogen and
cellulose
Carbon Compounds
 Lipids




Mostly carbon and hydrogen
Used to store energy
Important in membranes and waterproof
coverings
Referred to as saturated (solid) and
unsaturated (liquid)
Carbon Compounds
 Nucleic




acids
Made of hydrogen, oxygen, nitrogen, carbon
and phosphorus
Store and transmit hereditary or genetic
information
Nucleotides – monomers
Two kinds – RNA and DNA
Carbon Compounds
 Proteins




Made of nitrogen, carbon, hydrogen, and
oxygen
Control the rates of reactions and regulates
cell process
Also used for structure and transport
Amino acids – monomer
Chemical Reactions and Enzymes
 Chemical

Reactions
A process that changes or transforms, one set
of chemicals into another
• Changes in chemical bonds


Reactants – what is put into the reaction
Products – what is gotten out of the reaction
Chemical Reactions and Enzymes
 Energy


in Reactions
Either released or absorbed when bonds are
formed or broken
Energy sources – examples
• Plants – sunlight
• Animals – consumption (eating) and digesting

Activation energy – energy needed to get a
reaction started
Chemical Reactions and Enzymes

Enzymes


Specialized proteins
Biological catalyst – speeds up the rate of a chemical
reaction
• Lower activation energy


Very specific – one enzyme one chemical reaction
Substrates – the reactants of an enzyme catalyzed
reaction
• Bind at active site (lock and key)

Affected by things such as temperature or pH