Atom Basic unit of matter

Subatomic particles Protons - Neutrons - Electrons - Positively charged (+) Not charged (neutral) Negatively charged (-) Bind together to form the nucleus Electrons Protons Neutrons Nucleus

Element A pure substance that consists of just one type of atom

6 C Carbon Atomic number An elements atomic number = number of protons

Isotope Atoms of the same element that differ in the number of neutrons they contain

Nonradioactive carbon-12Nonradioactive carbon-13Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 8 neutrons 6 electrons 6 protons 7 neutrons

6 C Carbon Mass number The Sum of protons and neutrons in the nucleus of an atom is its mass number

Atomic Mass The weighted average of the masses of an elements isotope is called its atomic mass

Radioactive isotopes Can be dangerous Can be used practically –Radioactive dating –Treat cancer –Kill bacteria

Compounds A substance formed by the chemical combination of two or more elements in definite proportions Ex) H 2 O, NaCl

Table Salt

Ionic Bonds Formed when one or more electrons are transferred from one atom to another

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na + ) Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

If an atom loses an electron it becomes positive Ex: All metals If an atom gains an electron it becomes negative Ex:All nonmetals

Ions Positively and negatively charged atoms

Covalent Bonds Forms when electrons are shared between atoms

Molecule The structure that results when atoms are joined together by a covalent bond Both elements are nonmetals Smallest unit of most compounds

Van der Waals Forces A slight attraction that develops between the oppositely charged regions of nearby molecules due to unequal sharing of electrons

Homework Questions and Answers

1.Describe the structure of an atom. Atoms are made up of protons and neutrons in a nucleus. Electrons are in constant motion in the space around the nucleus. 2.Why do all isotopes of an element have the same chemical properties They have the same number of electrons

3. What is a covalent bond? A bond formed when electrons are shared between atoms 4. What is a compound? How are they related to molecules A compound is a substance formed by the chemical combination of two or more elements in definite proportions. A molecule is the smallest unit of most compounds

5. How do Van der Waals forces hold molecules together? When the sharing of electrons are unequal, a molecule has regions that are charged. An attraction can occur between oppositely charged regions of nearby molecules

6. How are ionic bonds and Van der Waals forces similar? How are they different? In both cases, particles are held together by attractions between opposite charges. The difference is that ionic charges are stronger

Section 2: Properties of Water

Objectives Why are water molecules polar? What are acidic solutions? What are basic solutions?

Basic information about water Formula for water: H 2 O Structure of a water molecule:

The solid lines between the O and the H represent covalent bonds In covalent bonds, electrons between the atoms are shared.

In some kinds of molecules, the electrons are shared equally between two atoms. 6. We say that those are nonpolar covalent bonds.

In water, though, oxygen and hydrogen do NOT share their electrons equally with each other so we say that there is a polar covalent bond between them.

Because the oxygen atom is pulling negative charges toward itself, this makes oxygen take on a partial negative charge.

9. The hydrogen atom is having negative electrons pulled away from it, so the 2 hydrogen atoms will take on a partial positive charge.

When another water molecule comes in, the partial negative oxygen of one water molecule will hydrogen bond with the partial positive hydrogen of another water molecule.

11. Hydrogen bonds are very weak, but they are very important in molecules like DNA and proteins.

Hydrogen bonds are also responsible for the many properties of water, such as: A. Cohesion: the attraction of molecules of the same kind (water molecules to other water molecules)

B. Adhesion: the attraction among molecules of different substances (water molecule to something else)

The Big Idea Much of our planet is covered in water Water is necessary for life to exist If life exists on other planets, there most likely is water present Water has many properties that make life possible

Polarity (-) (+) The oxygen atom has a stronger attraction for electrons

Hydrogen Bonds Because of waters partial charges, they can attract each other and create hydrogen bonds Not as strong as covalent or ionic bonds Waters ability to create multiple hydrogen bonds gives it many special properties

Cohesion Attraction between molecules of the same substance

Adhesion Attraction molecules of different substances

Mixture Material composed of two or more elements or compounds that are physically mixed but not chemically combined Ex.) salt & pepper, earths atmosphere

Solutions Mixture of two or more substances in which the molecules are evenly distributed Ex.) salt water Settles out over time

Solutions Cl - Water Cl - Na + Water Na +

Solute Substance that is dissolved Ex.) salt

Solvent The substance that does the dissolving Ex.) Water

Suspensions Mixture of water and non- dissolved materials Separate into pieces so small, they never settle out Ex: water and oil

Types of solutions A dilute solution is weak solution A concentrated solution is strong. An unsaturated solution contains less dissolved solute than it can hold at a given temp. A saturated solution contains all of the solute it can hold at a given temp. A Super saturated solution containing more solute than it can normally hold at a given temp. ( Crystals are often seen in this type of solution).

What is the pH scale? measure of the concentration of hydrogen ions in a solution Always shows reading between 0-14 pH between 0-7 is an acid pH between 7-14 is a base pH 7 is neutral. neutral: neither acidic nor basic

*Tastes sour *Conducts electricity *Corrosive to skin *Can eat through metal *Formulas starts with “H” *Always releases hydrogen ions (H+) when dissolved in water *pH is between 0-7 What is an acid?

* Tastes Bitter *Conducts electricity *Corrosive to skin *Feel slippery *Formulas ends with “OH” *Always releases hydroxide ions (OH¯) when dissolved in water *Red litmus paper into Blue (indicator) *pH between 7-14 What is a base?

What are indicators? substance that changes color in an acid or a base

What is neutralization? reaction between an acid and a base to produce a salt and water

What is an electrolyte? electrolyte : substance that conducts an electric current when it is dissolved in water ionization : formation of ions Nonelectrolyte: substance that will not conduct an electric current when it is dissolved in water.

Neutral Acid Base

Buffers Weak acids or bases that can react with strong acids or bases to prevent sharp, sudden pH changes

Homework Questions and Answers

1.Use the structure of a water molecule to explain why its polar Oxygen atom has greater attraction for electrons, therefore the oxygen atom is negative and the hydrogen end is positive

2. Compare acidic and basic solutions in terms of their H + ion and OH - ion concentrations Acid have more H + ions than OH - ions, and bases have more OH - ions than H + ions

3. What is the difference between a solution and a suspension? In a solution, all components are evenly distributed. In a suspension, un-dissolved particles are suspended

4. What does pH measure? The concentration of H + ions in a solution 5. The strong acid hydrogen floride (HF) can be dissolved in pure water. Will the pH of the solution be greater or less than 7? less than 7

Section 3: Carbon Compounds

Objective What are the functions of each group of organic compounds?

Most of the compounds that make up living things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms. As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain. Section 2-3 Interest Grabber Life’s backbone

MethaneAcetyleneButadieneBenzene Isooctane

Macromolecules “giant molecules” Formed by a process called polymerization

Monomers Smaller units

Polymers Linked up monomers

Carbohydrates Compounds made up of carbon, hydrogen, and oxygen atoms usually in a ratio of 1:2:1 Main source of energy The monomers of starch are sugars

Single sugar molecules are called monosaccharides The large macromolecules formed from monosaccharides are known as polysaccharides

Starch Glucose

Lipids Made mostly from carbon and hydrogen atoms Used to store energy

Lipid Glycerol Fatty Acids

Proteins Macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen Proteins are polymers of molecules called amino acids

Amino Acids General structureAlanineSerine Carboxyl group

More than 20 different amino acids, can join to any other amino acid The instructions for arranging amino acids into many different proteins are stored in DNA Each protein has a specific role The shape of proteins can be very important

Proteins Amino Acids

Nucleic Acids Macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus Double Helix

Nucleotides Consists of 3 parts: 5-carbon sugar, phosphate group and nitrogen base Nitrogen Base 5-Carbon Sugar Phosphate group

2 kinds of nucleic acids RNA (ribonucleic acids) – contains sugar ribose DNA (deoxyribonucleic acid) – contains sugar deoxyribose

Homework Questions and Answers

1.Name four groups of organic compounds found in living things carbohydrate, lipid, protein, nucleic acids 2. Describe at least one function of each group of organic compounds carbohydrates – energy lipids – store energy proteins – form tissue nucleic acids – transmit hereditary information

3. Compare the structures and functions of lipids and starches Lipids are made from carbon and hydrogen. Starches are made of carbon, hydrogen and oxygen. They both can be used to store energy