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55 Cards in this Set
- Front
- Back
Distinguish between an atom, molecule, element and compound
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Element- simplest form of a substance, one or more of a single type of atom
Molecule- two or more chemically bound atoms Compound- two or more different types of atoms |
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Difference between Law & Theory
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Scientific laws descibe observations, they don't explain them. Theories provide an explanation which incorporates facts, laws, inferences, & tested hypotheses
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Avogadro's Number Equals...
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One mole - which is the number of atoms or molecules present in a sample of an element or compund with a mass equal to its atomic or molecular mass expressed in grams
6.02 * 10^23 |
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What is Atomic Mass?
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The mass of one mol of each particular atom
Units in g/mol 1 mol N atoms = 14g 1mol Pb atoms = 207.2g |
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Calculate the Mm of H2O
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(2*1 g/mol)+(1*16 g/mol) = 18g/mol
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Conversion Process
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Grams of a Substance ⇆ Moles of a Substance ⇆ Number of Particles
(150g of S_8 ⇆ 0.6 mol S_8 ⇆ 3.6*10^22 molecules of S_8) |
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O2 = How many mol oxygen molecule?
How many mole of oxygen atom? |
1 mol oxygen molecule
2 mol oxygen atom |
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Limiting Reactant
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The reactant which is used up completely in a reaction. The other is in excess.
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(A/Z) X ^n
What do A, Z, & n represent? |
(A)=Mass number - # of protons +# of neutrons
(Z)=Atomic number - # of protons (often omitted) (n)=charge ( - or + ) |
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Isotope
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atoms that have the same number of protons (are the same element) but have different number of neutrons
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Cations
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ions with more protons than electrons
#p > #e Na - e- → Na+ |
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Anions
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ions with less protons than electrons
#p < #e Cl + e- → Cl- |
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Element. List some examples
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A substance is composed of identical atoms. Gold, silver, oxygen, hydrogen, lead, chlorine, helium, iron, copper, fluorine, arsenic
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Compound. List some examples
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substance composed of two or more elements chemically combined. Water - H2O; Salt - NaCl; Sugar - C6H12O6; Ammonia - NH3
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Atomic Number: What are the atomic numbers of helium, hydrogen, carbon, oxygen?
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The number of protons in the nucleus of an atom of an element. Helium-2; carbon-6; hydrogen-1; oxygen-8
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Mass number
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The sum of protons plus neutrons n the nucleus of an atom
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Molecule
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A group of two or more atoms held together by chemical bonds
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Ion (provide examples)
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An atom or group of atoms which contains a positive or negative electrical charge (ex. Na+; Cl-; SO4^2-)
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Cation and Anion (provide examples)
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cation - positively charged ion (Na+; Fe+2; NH4+; Ag+); anion - negatively charged ion (Cl-; SO4-2; OH-; P-3)
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Valence electroncs
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The electrons found in the outermost energy level of an atom
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Oxidation number
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A number (positive or negative) representing the charge on an ion or atom involved in a chemical bond
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Three general rules for determining oxidation numbers
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1) Atoms of uncombined elements equal 0; 2) Hydrogen = +1 (in metallic hydrides =-1); 3) Oxygen = -2 (in peroxides =-1); (bonded with fluorine =+2)
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Positive Ion: which elements tend to form them?
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Metals tend to form positive ions by losing electrons (Na → Na+ e-)
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Negative Ion: which elements tend to form them?
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Non-metals form negative ions by gaining electrons (Cl +e- →Cl-)
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Atomic Mass
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A weighted average mass of the atoms of an element (assuming the carbon-12 isotope is exactly 12) (ex. Atomic mass of C=35.45 is calculated from two isotopes. Cl-35 and Cl-36)
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For any substance, write a general formula to convert from Moles to Grams
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g=(n)(MM) where, n = moles MM = molecular mass g = grams
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For any substance, write a general formula to convert from Grams to Moles
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n = g/MM; n = moles; MM = molecular mass; g = grams
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For any substance, write a general formula to convert from Moles to Number of Particles
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(n)(6.02x10^23) = P; n = number of moles; P = number of particles
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For any substance, write a general formula to convert from Number of Particles to Moles
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n = P/6.02x1023; n = number of moles; P = number of particles
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Reactants; Products
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1) The starting materials in a chemical reaction; 2) The substances formed in a chemical reaction
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Balance Equations: H2 + N2 ↔ NH3; NaCL + Br2 ↔ NaBr + Cl2
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1) 3H2 + N2 ↔2NH3; 2) 2NaCl + Br2 ↔2NaBr + Cl2
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Period
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A horizontal row of elements in the periodic table. All have the same number of shells of e-. Across the period, the elements' properties change.
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Column or Family
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A verticle group of elements on the periodic table in the same column. They have similar properties and the same number of valence electrons.
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Describe the change in atomic radius across the periodic table
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The atomic radius tends to decrease from left to right across the table and increase down the columns
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Ionization energy
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The energy change required for the removal of the outermost electron from the gaseous atom to form a +1 ion
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Describe the change in Ionization Energy across the periodic table
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Ionization energy tends to increase from left to right across the table and decrease down the columns
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Quantum Number
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A number used to describe the energy levels available to an electron. Each electron in an atom has a unique set of four.
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Ground State
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Electron is at its lowest energy level as close to the nucleus as possible
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Excited State
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An electron absorbs energy and moves to a higher energy level above the ground state
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List the names of the four sublevels and their electron capacities
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sublevel s holds two electrons; p holds 6; d holds 10; f holds 14
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Which sublevels are present in energy levels 1, 2, 3, and 4-7?
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1: s; 2: s, p; 3: s, p, d; 4-7: s, p, d, f
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Describe the shapes of the orbitals: 1) s; 2) p; 3) d; 4) f
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1) s- sphere; 2) p - dumbbell shape with 2 lobes; 3) d - double dumbbell; most have 4 lobes; 4) f - most have 8 lobes
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What is the order for filling sublevels (aufbau process) from lowest to highest energy
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1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d
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Electron configuration
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The distribution of electrons into shells and sublevels for an atom of an element. Each element has a unique electron configuration.
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Valence
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The number of electrons in the atom's highest numbered shell.
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List the four steps of the scientific method
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1. observation & collection of quantitative or qualitative data
2. formulation of a hypothesis to explain the observation 3. prediction based on the hypothesis 4. testing the prediction |
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Nature seeks a position of _________energy and favors a change in E that is __________
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Lowest
Negative |
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Electromagnetic Force
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When charged particles are brought together, the are either attracted, or repelled by each other
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Coulomb's Law
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Energy = Force * Distance
E ~ q1q2 / r |
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For attractive forces, E is _________
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Negative
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For repulsive forces, E is ___________
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Positive
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When a proton and an electron move apart, there is a(n) _______ in energy
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Increase
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All waves travel at ___________
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The speed of light
(c) = 2.998 * 10^8 ms^-1 |
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Long wavelength =
______________ frequency & _________________ energy |
Low
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short wavelength =
_________ frequency & ___________ energy |
High
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