Chapter 2 Section 1

Chapter 2 Section 1

The Nature of Matter

• The basic unit of matter is the atom- the subatomic particles that make up matter are protons, neutrons and

electrons.• Protons have slightly positive charge (+)• Neutrons are neutral with no charge• Electrons have slightly negative charge (-)• Protons and Neutrons are found in the nucleus

of an atom and have about the same mass• Electrons have a mass of about 1/1840 of a

proton

• Elements are pure substances made entirely of ONE type of atom found in nature

Ex: H = hydrogenO = oxygenNa = sodiumFe = iron

• Isotopes are atoms of the same element that differ in the # of neutrons

- identified by their mass number- all isotopes of the same element have the same chemical properties

• Isotope examples:The element CARBON

Carbon 126 electrons6 protons

6 neutrons

Carbon 136 electrons6 protons

7 neutrons

Radioactive Carbon 14

6 electrons6 protons

8 neutrons

• A compound is a substance formed by the chemical combination of two or more elements

Ex: Water (2:1 ratio) 2 hydrogens1 oxygen

NaCl (1:1 ratio) 1 sodium1 chloride

Chemical Bonds

• 2 main types of chemical bonds are ionic and covalent

• Ionic bonding occurs when one or more electrons transfers from one atom to another

- When an atom loses an electron, it becomes positively charged.

- When an atom gains an electron, it becomes negatively charged.

• Covalent bonding occurs when atoms share electrons

• When atoms are joined together covalently, molecules are formed.

- molecules are the smallest unit of a compound

• Atoms of different elements attract electrons differently and therefore, van der Waals forces exist.

- describes intermolecular forces of attraction- NOT as strong as ionic or covalent bonding- can hold larger molecules together

Ex. A gecko climbing a vertical surface

Chapter 2 Section 2

Properties of H2O

• Water molecules are neutral. They have 10 protons and 10 electrons.

• A molecule of water has a bent shape. The hydrogen side has a slightly positive polarity. The oxygen side has a slightly negative polarity.

- oxygen has 8 protons in its nucleus- hydrogen has 1 proton in its nucleus

• A water molecule is polar because there is an uneven distribution of electrons between the oxygen atom & hydrogen atom.

• Oxygen has a much stronger attraction to electrons than hydrogen. Thus, resulting in a polar molecule. - cohesion – attraction between molecules of the same substanceEx: H2O forms beads on surfaces, the molecules are drawn inward. - adhesion – attraction of molecules of different substances

• Water is not always pure, it may be part of a mixture.• A mixture is material composed of two or more elements

or compounds that are physically mixed, NOT chemically. Ex: sugar & sand salt & pepper

• A solution has materials evenly distributed throughout. - solute – is dissolved- solvent – does the dissolvingEx. NaCl + H2O (solute) (solvent)

***WATER IS KNOWN AS THE UNIVERSAL SOLVENT***

• A suspension is a mixture of H2O and undissolved particlesEx: blood

• pH is a measure of the concentration of hydrogen in a solution (refer to page 43 in text) - The pH scale ranges from 0-14- acids (0-6) high hydrogen ion concentration- bases (8-14) high hydroxide ion concentration- neutral (7) neutral concentration

Chapter 2 Sec 3

Carbon Compounds

The Chemistry of Carbon

• We call the study of all compounds that contain bonds between carbon atoms, organic chemistry.

• Carbon atoms have 4 valence electrons that may bond with another atom of a different element.

• Carbon most commonly bonds with hydrogen, oxygen, phosphorus, and sulfur.

• Carbon can also bond with other carbon atoms which allows them to form chains.

• Carbon-carbon compounds can be single, double or triple covalent bonds.

• Carbon is very versatile.

Macromolecules

• Means “giant molecule”• Most molecules in living organisms are

macromolecules. • Made from thousands to hundreds of

thousands of smaller molecules.• Form by the process of polymerization, in

which larger molecules are made by joining smaller molecules.

• Smaller units (monomers) join together to form larger molecules (polymers).

• The four groups of organic compounds (macromolecules) are:

1. Carbohydrates2. Lipids3. Nucleic acids4. Proteins

Carbohydrates

• Compounds made up of carbon, hydrogen and oxygen atoms (in a 1:2:1)

• Living things use carbs as their main source of energy.

• Plants and some animals use carbs for structural purposes.

• Starches (complex carbs) and sugars are examples of carbs used by living things as a source of energy.

• Sugars are monomers for a starch molecule.

• Single sugar molecules are monosaccharides• Larger molecules formed from

monosaccharides (galactose in milk, fructose and fruit) are polysaccharides (glycogen an animal starch)

Lipids

• Not soluble in water• Made mostly from carbon and hydrogen atoms• Fats, oils and waxes• Lipids are used to store energy, parts of biological

membranes and waterproof coverings• Steroids are lipids – used to carry chemical messages

through the body• Saturated – when the fatty acid contains the maximum

number of H atoms• Unsaturated – when there is at least one carbon-carbon

double bond in the fatty acid

Nucleic Acids

• Macromolecules containing hydrogen, oxygen, nitrogen, carbon and phosphorous.

• They are polymers made of monomers called nucleotides

• Nucleotides consist of a 5-carbon sugar, phosphate group and a nitrogenous base

• Nucleotides join by covalent bonds to form a nucleic acid

• Nucleic acids store or transmit heredity/genetic information.

• Two kinds:1. Ribonucleic acid (RNA)2. Deoxyribonucleic acid (DNA)

• RNA is a single sugar molecule (ribose)• DNA is a double sugar molecule

(deoxyribose)

Proteins

• Macromolecules that contain nitrogen, carbon, hydrogen and oxygen

• Polymers of amino acids (amino acids folded into complex structures)

• Amino acids are compounds with an amino group and a carboxyl group

• More than 20 different amino acids are found in nature• Proteins control the rate of cell reactions• Some proteins form bone and muscle• Other proteins transport substances into and out of the cell

• Proteins have up to 4 levels of organization:

1. sequence of amino acids2. twisted or folded3. chain is folded4. Van der Waals forces to hold together

Chapter 2 Section 4

Chemical Reactions and Enzymes

• A chemical reaction occurs when one set of chemicals is changed into another set of chemicals.

• Chemical reactions always involve changes in chemical bonds. (breaking bonds and forming new bonds)

• The elements or chemical components that ENTER into a chemical reaction are known as reactants.

• The elements or chemical components that are PRODUCED in a chemical reaction are known as products.

• All reactions use and produce energy. - Chemical reactions that release energy often occur spontaneously. - Chemical reactions that absorb energy need an energy source. - Activation energy is needed to get a reaction going. - A catalyst is something that speeds up a reaction (ex. Heat)- Enzymes are proteins that act as biological catalysts within cells. - Cells use enzymes to speed up chemical reactions. -Enzymes lower the activation energy needed for a reaction to begin.

Reactions and Energy

• Endergonic Reactions: energy is taken in for the reaction to take place (energy is used)

• Exergonic Reactions: energy is released

Enzyme Action

• The reactants for an enzyme catalyzed reaction are called substrates

• Enzymes are substrate specific: think of a lock and key

• Once the enzyme binds to the active site of a substrate, an enzyme-substrate complex is formed

• The reaction occurs, the products are released, and the enzyme changes back to its original conformation

• E + S E-S COMPLEX E + P