BASIC CHEMISTRY I thought this was biology? Objective: 1.To Understand what causes chemical bonds 2.To be able to read an equation 3.To Understand polarity 4.To understand acids and bases Activities: 1.Take notes 2.Take the knowledge check

Atomic Theory of Matter Living and non-living things are made of same building blocks. MATTER is made of ATOMS in different combinations. ATOMS = smallest unit of matter

Terms to Know… ELEMENT = Substance made of only ONE kind of atom & cannot naturally be broken down further. e.g. See Periodic Table of Elements, there are over 100 known elements, 92 of which occur naturally. Each element has a unique name and symbol. COMPOUND = Made of 2 or more different kinds of atoms which can be separated into single elements. e.g. H ² O is a compound made of Hydrogen and Oxygen

Periodic Table of Elements Horizontal rows are called periods Vertical columns are called groups

Atomic Structure: Subatomic Particles PROTON = particle carrying + charge NEUTRON = particle carrying NO charge Protons and neutrons have equal mass ELECTRON = particle carrying – charge Electrons have NO significant mass.

Structure continued… NUCLEUS = Center of the atom, contains 1 or more protons. MAY also contain neutrons

Structure continued… Electrons are found ORBITING the nucleus in ENERGY LEVELS or ELECTRON CLOUDS.

Exploring Energy Levels Electrons occupy levels at different distances from the nucleus. 1 st Level holds ONLY 2 electrons 2 nd Level holds UP TO 8 electrons 3 rd Level holds UP TO 8 electrons When the outermost level of an atom is filled completely, that atom is called STABLE & does not form bonds. If an atom’s outermost energy level is not completely filled, it is called UNSTABLE & forms bonds.

Compounds Review A pure substance formed when two or more different elements combine Compounds are always formed from a specific combination of elements in a fixed ratio Compounds cannot be broken down into simpler compounds or elements by physical means

ATOMIC NUMBER # of Protons in an atom Usually # protons = # electrons Makes the Overall Charge neutral E.g. Oxygen’s atomic number = 8 An Oxygen atom has 8 protons How many electrons does it have? Look up Nitrogen Nitrogen’s atomic number = 7 Nitrogen has 7 protons and 7 electrons

Mass Number (aka Atomic Mass) # protons PLUS #neutrons, so Mass = P + N E.g. Oxygen’s Mass = 16 (remember that’s protons plus neutrons) We know Oxygen has 8 protons, so if 8 of the 16 particles are protons, then the remaining 8 particles must be? If Mass = P + N, then 16 = 8 + N N must be…8! Therefore, Oxygen has 8 Neutrons

Isotopes Atoms of the same element with varying # neutrons This changes mass number (remember, mass = P + N), but the atomic number stays the same (P) E.g. Some Oxygen atoms have a mass of 17 or 18. What are the numbers of subatomic particles for each isotope?

Let’s Practice…. 1. Find Symbol 2. Atomic # 3. Mass # 4. # protons, electrons and neutrons Hydrogen Helium Nitrogen Sodium Chlorine

Formulas… Chemical Formula (aka Molecular Formula) Each element is represented by its chemical symbol & proportions E.g. Water = H 2 O and Carbon Dioxide = CO 2 Structural Formula Each element is represented by its chemical symbol, proportion AND how the atoms bond together (structure) E.g. Carbon DioxideO=C=O 1 line is 1 bond, 2 lines are 2 bonds, etc.

Reactants and Products A chemical reaction is the process by which atoms or groups of atoms in substances are reorganized into different substances. Clues that a chemical reaction has taken place include the production of heat or light, and formation of a gas, liquid, or solid.

Chemical Equations Chemical formulas describe the substances in the reaction and arrows indicate the process of change Reactants: the starting substances, on the left side of the arrow Products: are the substances formed during the reaction, on the right side of the arrow.

Balancing Equations

Chemical Bonds Ionic Bond = Transfer of an electron from one atom to another. The atom that gains an electron becomes NEGATIVELY charged, called a NEGATIVE ION The atom that loses an electron becomes POSITIVELY charged, called a POSITIVE ION The 2 ions are attracted to each other, creating an IONIC BOND

Ionic bond example…NaCl (Sodium Chloride)

Covalent Bonds Covalent: Chemical bond that forms when 2 atoms SHARE an electron PAIR (other examples: H 2 or H 2 O) A molecule is a compound in which the atoms are held together by covalent bonds. Carbohydrates DNA Protein Lipids Remember: 1 shared pair = 1 Covalent Bond

Hydrogen Bond A weak chemical attraction between 2 polar molecules, a positive hydrogen atom and a negatively charged fluorine, oxygen or nitrogen atom. Polar molecules have a positive charge on one end and a negative charge on the other end. Polarity is the property of having two opposite poles.

Properties of Water Oxygen shares a pair of electrons with EACH Hydrogen The sharing is not equal! Oxygen has higher attraction for the electrons, so they are held closer to the oxygen atom giving it a partial – charge, and each hydrogen has a partial + charge. (see handout) Molecules with partial + and – charges are called polar molecules. Cohesion = when + end of a polar molecule is attracted to the – end of another polar molecule of the same substance. Adhesion = the force of attraction between a molecule of one substance and a molecule of another substance. (e.g. meniscus)

Water’s Polarity

Oil and Water Oil is nonpolar Water is polar This is why they don’t mix.

Acids and Bases Substances that release hydrogen ions (H + ) when dissolved in water are called acids. Substances that release hydroxide ions (OH - ) when dissolved in water are called bases Basic solution Acidic solution Substance with OH - ion Substance with H + ion H + OH -

pH The measure of concentration of H + in a solution is called pH. Acidic solutions have pH values lower than 7. Basic solutions have pH values higher than 7.

Organic Chemistry Carbon has four electrons in its outermost energy level. One carbon atom can form four covalent bonds with other atoms. Carbon compounds can be in the shape of straight chains, branched chains, and rings.

Bibliography mediaviewer/File:Helium-Bohr.svg mediaviewer/File:Helium-Bohr.svg e#mediaviewer/File:IUPAC_Periodic_Table_modified.PN G e#mediaviewer/File:IUPAC_Periodic_Table_modified.PN G jpg 01.jpg nt_Bonds_in_a_Water_Molecule.jpg nt_Bonds_in_a_Water_Molecule.jpg ClipArt