Post Assessment - Chemistry
Roman Numerals
1 = I 2 = II 3 = III 4 = IV 5 = V 6 = VI 7 = VII 8 = VIII 9 = IX 10 = X
What are the names of each group on the periodic table?
1: Alkali Metals (except Hydrogen) 2: Alkaline Earth Metals 3-12: Transition Metals 13: Boron Group 14: Carbon Group 15: Nitrogen Group 16: Oxygen Group 17: Halogens (salt former) 18: Noble Gases 4f: Lanthanides 5f: Actinides 1, 2, 13-18: Main Group Elements, Representative Elements 4f, 5f: Rare Earth Metals, Inner Transition Metals
Electron Configuration for Br
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵
What is an ionic compound? What is its representative particle?
A bond between a metal/nonmetal or cation/anion where the valence electrons are transferred (not shared), formula unit
What is a covalent compound? What is its representative particle?
A bond between two nonmetals or a nonmetal/metalloid where the valence electrons are shared, molecule
What is Avogadro's number and what is it equal to?
Avogadro's number is the number of particles in a mole, 6.022 x 10²³
How do you find wavelength (λ)?
C/v = λ (C = speed of light, 3.00 x 10⁸ m/s)
Which elements can multiple bond (double and triple)?
Carbon, Oxygen, Nitrogen, Sulfur (CONS)
What units are used for density? mass? volume?
Density = grams per cubic centimeter (g/cm³) or grams per milliliter (g/mL) Mass = grams (g) Volume = milliliter (mL) or cubic centimeter (cm³)
What is the formula for density?
Density = mass/volume (D = m/v)
Who developed the first period table?
Dmitri Mendeleev
What are the two types of covalent bonds?
Polar covalent and nonpolar covalent
What particles are in the nucleus?
Protons and neutrons
What are the symbols for solid, liquid, gas, aqueous, and yields?
(s), (l), (g), (aq), →
What are the properties of metalloids?
- Exhibit both metallic and nonmetallic properties - Solids - Semiconductors
How do you determine the sig figs needed when doing addition and subtraction?
- Least number of digits to the right of the decimal point (does not matter if the numbers are sig figs or not, you still do the least amount of numbers) - If a number ends in exactly 5 and you have to round - If the number before 5 is even, leave it - If the number before 5 is odd, round it Example: 7.91 + 5.3 = 13.21, but the sig fig answer would be 13.2
What are the properties of metals?
- Luster (reflects light, shiny) - Good reflectors of heat and light - Good conductors of heat and electricity - Valence electrons are held loosely and free to move, so they can conduct well - Ductile - Malleable - Tenacious
What are the properties of nonmetals?
- Poor conductors - Tightly held valence electrons which means electricity cannot flow - Non-ductile - Non-malleable - Non-tenacious - Gas, brittle solid
What are the properties of ionic compounds?
- high melting and boiling point - solid at room temperature - hard, but brittle - not conductors in the solid state, but when dissolved in water they can conduct (electrolytes)
What are the properties of covalent compounds?
- low melting and boiling point - usually gases, liquids, or soft solids - not conductors
Prefixes
1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa- 9 = nona- 10 = deca-
Sig Fig Rules
1. Every nonzero digit in a recorded measurement is significant (ex. 38.2 has 3 sig figs) 2. Zeros appearing between two significant digits are always significant (ex. 9001 has 4 sig figs) 3. Zeros appearing in front of all nonzero digits are not significant. They are acting as place holders (ex. 0.007 has 1 sig fig) 4. Zeros at the end of a number and to the right of a decimal point are significant (ex. 43.00 has 4 sig figs) 5. Zeros at the end of a measurement and to the left of a decimal point are not significant unless marked (ex. 300 has 1 sig fig)
Put the number 0.000576 into scientific notation
5.76 x 10⁻⁴
What does ABE stand for?
A = Central atom B = Number of atoms attached to the central atoms E = Unshared pairs on the central atom
What is a group and how many are there?
A group is a column down the periodic table, 18
What is an octet?
A group of 8 valence electrons
What is Electronegativity?
A measure of the ability of an atom in a compound to attract electrons from another atom
What is an anion?
A negatively charged ion
What are unshared pairs?
A pair of valence electrons that are not shared with another atom in a covalent bond
What is a period and how many are there?
A period is a row across the periodic table, 7
What is a cation?
A positively charged ion
What is an element?
A substance found on the periodic table that can not be broken down into a simpler substance
What is a nonelectrolyte?
A substance that does not have an electrical charge when dissolved in water
What is an electrolyte?
A substance that has an electrical charge when dissolved in water
What is a mole?
A unit of a substance with as many particles as there are atoms
Draw SO₂ and determine the ABE, geometry, polarity, and intermolecular forces involved
ABE = AB₂E Geometry = bent Polarity = polar covalent Intermolecular Forces = London Dispersion forces, dipole-dipole force
What is the charge of Silver (Ag)? Zinc (Zn)? Cadmium (Cd)?
Ag = 1⁺ Zn = 2⁺ Cd = 2⁺
What is Ionic Radius?
An ion is an atom or group that has + and - charge - cation (+, lose e⁻) - anion (-, gain e⁻)
How do you find frequency (v)?
C/λ = v (C = speed of light, 3.00 x 10⁸ m/s)
What does ductile mean?
Can be drawn into wire
What does malleable mean?
Can be hammered or rolled into sheets
What is the trend for Ionic Radius?
Cation - loses electrons causing a decrease in atomic radius Anion - adds electrons causing an increase in atomic radius
What do you do if the electronegativity is or between 1.7 - 1.9?
Check the elements to determine the type of bond
Which type of compound is weak, low melting point, and does not conduct electricity?
Covalent compound
What is the octet rule?
Each atom, by gaining, losing, or sharing electrons, has an octet of electrons in its highest level
What is a nonpolar covalent bond? What electronegativity difference ∆EN will give a nonpolar covalent bond?
Electrons are shared mostly equal, 0.0 - 0.4
What is a polar covalent bond? What electronegativity difference ∆EN will give a polar covalent bond?
Electrons are shared unequally (one element pulls harder), 0.5 - 1.6
When do we see light of a certain color given off by an element?
Electrons are sitting at the ground state, they are hit by/absorb a quantum of energy and jump up to the excited state, when they come back down they release a photon of energy in the form of light
What are valence electrons and where are they?
Electrons in the outermost (highest occupied) energy level. They are the ones involved in bonding/lost or gained.
Who discovered the proton and nucleus with the gold foil experiment?
Ernest Rutherford
Empirical Formula (for percentage)
First, assume all samples are based on 100%, so we can assume there is 100 grams of a sample (drop the percent sign, replace it was "g"). Second, convert the new grams samples to moles. Then, divide the moles answers by the smallest of the mol answers you got to get a whole number. If it's, for example, 1.9, round to 2. If you are not close to a whole number, you have to figure out what each of the numbers need to be multiplied by to get a whole number. Finally, add those whole numbers to their respective elements. (example: if your whole number after you divided for Mg was 3, you would write it as Mg₃)
Empirical Formula for Molar Mass (simple formula)
First, find the total molar mass of the elements in the compound. Then, divide the given g/mol number by the total molar mass of the elements. The number that results should be a whole number or very close so you can round. Nextly, multiple the whole compound by the resulting number as a subscript to get the unsimple formula. Molecular formula: molar mass over mass of simple = #. (simple formula)subscript # = molecular formula
What are the intermolecular forces?
Forces between molecules - London Dispersion Forces - every molecule has this force, weakest force, only force a nonpolar bond can have - Dipole-Dipole Force - polar molecules have this force - Hydrogen Bond - strongest force but not stronger than a covalent bond, only happens when H is attracted to N, O, and F on another molecule
If elements are similar, are they in the same group or period?
Group
How many valence electrons does each main-group family have?
Group 1: 1 Group 2: 2 Group 13: 3 Group 14: 4 Group 15: 5 Group 16: 6 Group 17: 7 Group 18: 8
What are the charges of each group on the periodic table?
Group 1: 1⁺ Group 2: 2⁺ Group 13: 3⁺ Group 14: 4⁺⁻ Group 15: 3⁻ Group 16: 2⁻ Group 17: 1⁻ Group 18: 0
How to write a Binary Acid
H and 1 other element (anion, CCN¹⁻ is the only exception) - "hydro" - root name element - "ic" - acid - example: HF = hydro-fluor-ic-acid → hydrofluoric acid
How to write an Oxyacid
H, O, and 1 other element (polyatomic ions) - "ate" = "ic" (nitrate → nitric) - "ite" = "ous" (nitrite → nitrous) - sulfur = sulfuric, sulfurous (keep "r") - phosphorus = phosphoric, phosphorous (keep "r") - no hydro in front
What are the diatomic elements?
Have No Fear Of Ice CoLd BeaRs
What are the exceptions to the octet rule?
Hydrogen (H) - can only have 1 bond (2 e⁻) Boron (B) - less than 8 e⁻ Period 3 or higher nonmetals could form expanded octets (more than 8 e⁻)
Which type of compound is strong, high melting point, and conducts electricity when dissolved (electrolyte)?
Ionic compound
Who discovered the electron?
J. J. Thomson
How do you determine the sig figs needed when doing multiplication and division?
Least number of significant figures Example: 56.7/7 = 8.1, but the sig fig answer would be 8
Foldable: Base units
Length: meters, measured with meter stick/ruler Mass: grams (g, base unit) and kilograms (kg, SI unit), measured with a balance Time: seconds, measured with a stopwatch Temperature: Celsius (°C, base unit) and Kelvin (K, SI unit), measured with a thermometer Liquid Volume: milliliters (mL, base unit) and liters (L, SI unit), measured with a graduated cylinder Solid Volume: cubic centimeters (cm³, base unit) and cubic meters (m³, SI unit), measured with a meter stick
Electromagnetic Spectrum (from least energy and longest waves to most energy and shortest waves)
Long waves, short waves, radio waves (AM and FM), microwaves, infrared, visible light (ROYGBIV), ultraviolet, x-ray, gamma ray
How do you find protons?
Look at the atomic number (for example, if the atomic number of H is 1, then the number of protons in 1)
What is the trend for Electron Affinity?
Main group elements (1, 2, 13-18) increases across a period Main group elements (1, 2, 13-18) decrease down a group
What is the trend for Electronegativity?
Main group elements (1, 2, 13-18) increases across a period Main group elements (1, 2, 13-18) decrease down a group
What is the trend for Ionization Energy?
Main group elements (1, 2, 13-18) increases across a period Main group elements (1, 2, 13-18) decrease down a group
What does the Law of Conservation of Mass say?
Mass cannot be created or destroyed, only altered in form
How do you find neutrons?
Mass number (rounded atomic mass) minus the atomic number
What kind of elements come together for ionic bonds? What do they do with their electrons?
Metal/nonmetal, complete transfer of electrons between atoms (electrons are not shared)
Where are the metals, nonmetals, and metalloids located?
Metals: left of the staircase Nonmetals: right of the staircase Metalloids: the staircase (B, Si, Ge, As, Sb, Te, Po)
Determine the electronegativity difference of N-O and identify the bond type
N = 3.0 O = 3.5 3.5 - 3.0 = 0.5 Bond type = polar covalent
Find the following for Zn - Name - Atomic Number - Mass Number - Protons - Electrons - Neutrons - Nuclear symbol
Name: Zinc Atomic number: 30 Mass number: 65.00 Protons: 30 Electrons: 30 Neutrons: 35 Nuclear symbol: 65 Zn 30
What kind of elements come together for covalent bonds? What do they do with their electrons?
Nonmetal/nonmetal or nonmetal/metalloid, they share their electrons
What is Atomic Radius?
One half the distance between nuclei of two identical atoms that are bonded
For [Ar] 4s²3d¹⁰4p³, what is the: - period - group - block - type of element
Period: 4 Group: 15 Block: p Type of element: metalloid (As)
What is the most common state of matter on the universe, both not Earth?
Plasma
What is the charge of a proton, electron, and neutron?
Proton - 1⁺ Electron - 1⁻ Neutron - 0
Which color of the visible spectrum is the most energetic?
Purple
Which color of the visible spectrum has the longest wavelength and least energy?
Red
What does tenacious mean?
Resists being stretched or pulled apart
What is an ionic bond? What electronegativity difference ∆EN will give an ionic bond?
Results from the electrical attraction of cations + anions (electrons are completely transferred from one element to another), 2.0 or higher
How do you find electrons?
Same as the number of protons unless there's a charge (negative charge means the element gains an electron, positive charge means the element loses an electron)
What is an isotope?
Same element with a different number of neutrons, which results in a different atomic mass than the original element
What is the trend for Atomic Radius?
Size decreases across a period (decrease →) Size increases down a group (increase ↓)
What are the states of matter? Which has the lowest density and which has the highest?
States of matter: gas, liquid, solid, plasma Lowest density: gas Highest density: solid
Foldable: SI Prefixes/Conversions
Tera (T) - 10¹² Giga (G) - 10⁹ Mega (M) - 10⁶ Kilo (k) - 10³ hecto (h) - 10² deca (da) - 10¹ base unit (g, L, m, s) - 10⁰ deci (d) - 10⁻¹ centi (c) - 10⁻² milli (m) - 10⁻³ micro (μ) - 10⁻⁶ nano (n) - 10⁻⁹ pico (p) - 10⁻¹²
What is a metallic bond?
The chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons
What is Electron Affinity?
The energy change that occurs when an electron is acquired by a neutral atom
What is Ionization Energy?
The energy required to remove an electron from a gaseous atom or ion (kJ, kilojoule/mol)
What is the periodic law?
The physical and chemical properties of the elements are periodic functions of their atomic numbers
What is a formula unit?
The simplest form of an ionic compound
Why are metals malleable, ductile, and conductive?
They are malleable, ductile, and conductive because the valence electrons are able to move around freely
What does endothermic mean?
To gain heat/energy
What does exothermic mean?
To release heat/energy
Which elements have more than one charge or positive oxidation number?
Transition Metals (Groups 3-12)
What is a compound?
Two or more elements chemically bonded
What is a mixture?
Two or more substances that can be separated physically
How do you calculate an electronegativity difference?
Using a periodic table with the electronegativities for the elements listed, find the electronegativity of the elements and subtract the smallest from the biggest (biggest electronegativity - smallest electronegativity, you do not want a negative electronegativity)
Why is water so strong and has unique properties?
Water molecules are polar, so they form a hydrogen bond, which is the strongest of the intermolecular forces. This gives it unique properties like a high boiling point.
When dealing with scientific notation, how can you tell if the exponent will be positive or negative?
When the number is less than one, there will be a negative exponent (ex. 0.0079 → 7.9 x 10⁻³) When the number is more than one, there will be a positive exponent (ex. 990000 → 9.9 x 10⁵)
Noble Gas Configuration for Se
[Ar] 4s²3d¹⁰4p⁴
When you calculate electronegativity and the bond is polar, which element gets the partial negative charge and which gets the partial positive charge?
higher electronegativity = partial negative charge lower electronegativity = partial positive charge
Visible Spectrum
image of the visible spectrum
Which elements want to lose electrons?
metals
Which elements want to gain electrons?
nonmetals
How many electrons can the s, p, d, and f sublevels hold?
s = 2 p = 6 d = 10 f = 14
