Chemistry Regents Review

The Atom Describe the atom. How do we “write” an atom?

Some experiments of note: Greeks view of nature J.J. Thompson’s cathode ray Ernest Rutherford’s gold foil experiment John Dalton’s Atomic Theory

Modern Atomic Theory: 1.The Bohr Model of the Atom a)“Planetary” model (K,L,M,N,O,P, and Q or 1-7) 2.The Wave-Mechanical Model a)Electrons move within an orbital b)An orbital is a region where an electron is most likely to be found. c)Energy.

Subatomic Particles 1.Protons and Neutrons -24 a) 1.67 x 10 g = about 1 amu 2.Electrons a) 1/1800 of an amu

Atomic Mass, Atomic Number, and Isotopes: Atomic mass is the number of neutrons plus the number of protons. Atomic number is the number of protons. This can never change for a particular element. What does that mean? An Isotope of an element will have different number of neutrons.

More electron stuff: Where are electrons located? What are energy levels, and how do electrons move between them?

Ground vs Excited 1.Ground state for sodium: 1.Na Excited State for sodium: 1.Na 2-7-2

Bright-line spectra for some elements:

Electon Arrangement: The four Quantum Numbers describe the location of an individual electron. Think address! No two electrons can have the same four quantum numbers.

Electron Configuration According to the Periodic Table If you can make a connection with the quantum numbers, electron configuration, and the Periodic Table, then you’ve got it made kid! Let’s try!

Types of Matter Homogeneous –Uniform composition throughout. –Ex/ elements, compounds, and apple juice,. Heterogeneous –Different composition throughout. –Ex/ chocolate chip cookie, and rocks in water.

Pure substance vs. Mixtures Pure substances include elements and compounds. Define them. Mixtures can be homogeneous or heterogeneous, are made up of two or more pure substances and can be separated by physical means. What does this mean?

Chemical Symbols What is a chemical symbol? What is it’s purpose? Draw the chemical symbol for your favorite element.

Diatomic Molecules Some elements exist in nature as two covalently bonded atoms. Make sure you always write with a subscript of 2. They are: O 2, H 2, N 2, F 2, Cl 2, Br 2, and I 2.

Chemical Formulas 1.Qualitative information. 1.Symbols. 2.Quantitative information. 1.Numbers.

More Formulas: Empirical Formula Lowest whole number ratio. Ex/ HO is the empirical formula for hydrogen peroxide. Molecular Formula Actual chemical formula. Ex/ H 2 O 2 is the molecular formula for hydrogen peroxide.

Ionic Charges Atoms and compounds are electrically neutral, but ions are not. A polyatomic ion is a group of atoms covalently bonded and possessing a charge. Many compounds form from oppositely charged ions attracting each other.

Writing Formulas and Naming Compounds: Stoichiometric Coefficients tell us how many there are of a certain molecule or substance. Ex/ 2H 2 O tells us that there are two molecules of water. Equalizing charges allows us to write the chemical formula of a molecule with the appropriate ratio of atoms/molecule. Ex/ Na+ and Cl- combine in a one to one ratio to make NaCl.

Naming Compounds Binary Ionic compounds: Positive ion first, negative ion second with “ide” ending. Ex/ sodium chloride. Binary Covalent compounds: Metal first, then non-metal. Or, if two non-metals, element with lower electronegativity goes first. Prefixes apply with “ide” ending. Ex/ carbon dioxide. The Stock System: Metals with more than one oxidation state. Ex/ Fe 2+ combined with oxygen is Iron (II) oxide.

Chemical Reactions and Equations: Physical Changes- –Often phase changes. No new substance is formed. Ex/ ice melting. Chemical Changes- –Represented by chemical equations. Reactants and products formed. Ex/ combustion of gasoline. A chemical reaction.

Chemical Equations:

Types of Chemical Rxs video: tE4668aarck tE4668aarck

Heat Reactions Endothermic –Surrounding temperature decreases, PE of products increases, and ΔH is positive. Ex/H 2 O(s) + energy → H 2 O(l) Exothermic –Surrounding temperature increases, PE of products decreases, and ΔH is negative. Ex/Ch 4 + 3O 2 → CO 2 + 2H 2 O + energy

Balancing Chemical Equations The Law of Conservation of Mass: –Says we need equal amounts on both product and reactant side of a chemical equation. –We can determine an unknown within a chemical formula based on this law. Example: –2H 2(g) + O 2 → 2H 2 O (g)

Balancing Chemical Equations video: 3xO2h74&NR=1&feature=fvwp 3xO2h74&NR=1&feature=fvwp