Mass = # of protons + # of neutrons
Average atomic mass = (% abundance atomic mass of isotope) + (% abundance atomic mass of isotope)
Density= mass/volume (heart)
Percent error = |Measure value-accepted value/ accepted value| * 100
Energy = planks constant * wavelength
Energy = Planks constant * speed of light / wavelength
Frequency = speed of light / wavelength
m2=m1(1/2)^(t2/t1)
m2=mass remaining
m1=original mass
t2=time
t1= half-life
Law | A statement that explains the relationship between variables. how it happens |
Theory | Answer to a question that has been tested and observed (can be proven wrong) |
Net ionic equation | A chemical equation that only shows the ions directly undergoing chemical changes in a reaction. |
Spectator ion | Ions that appear on both sides of the reaction and do not take part in the reaction. |
Precipitate | A solid formed by a change in a solution from a liquid solution. |
Amplitude | The height of the wave from the origin to the crest |
Wavelength | The distance from one crest to the next crest |
Quantum | A single piece of energy. The amount of energy that an object emits or absorbs is restricted. Each piece of energy is a quantum. |
Orbital | Energy levels that electrons revolve in. (s, p, d, f) |
Valence electron | Electrons in the outermost shell of an atom, that participate in chemical bonds. |
Periodic law | When elements are arranged by increasing atomic number, their chemical properties and physical properties show a pattern. Todays periodic table is arranged according to the periodic law. |
Periodic trend | The arrangement of the periodic table reveals trends or patterns such as increasing or decreasing in the size or tendencies of melting or bonding. |
Electronegativity | The ability of an atom to attract and hold an electron. ↗ You can determine the bond type using electronegativity (find the difference in the electronegative by subtracting the two values) |
Atomic radius | The size of an atom. Can be determined by calculating half of the distance between the nucleus of an atom to the nucleus of another bonding atom. ½ distance = bond radius. Increases from top right to bottom left ↙ |
Ionization energy | The energy needed to remove an electron ↗ |
Octet rule | Atoms tend to gain or lose electrons to acquire a full set of valence electrons which is stable. Atoms obtain stability when they have 8 valence electrons. |
Hydrate | A compound with H2O molecules in the compound. (compound that absorbs water) |
Anhydrous | A substance containing no water |
Polar bond | One atom attracts electrons more strongly than the other |
Nonpolar bond | Electrons are equally shared |
Error | The difference between a measured value and the true value of a substance or quantity. Accepted value- experimental value |
Precision | How close multiple measurements of the same item are to each other |
Accuracy | How close a measurement is to the true or known value |
Derived unit | When a unit is composed of various units. A combination of base units (from the international system of units or SI) Ex. area of a rectangle = length times width |
Ion | An atom that has gained or lost one or more electrons and has become electrically charged. Gains electrons = (-); anion Loses electrons = (+); cation |
Isotope | An element that has a different number of neutrons is called an isotope Ex: C-12, C-14 |
Chain reaction | A series of events, each caused by the previous one: Ex. nuclear fission |
Radioactivity | The spontaneous emission of radiation from an atom’s nucleus. Ex. alpha, beta, and gamma radiation consist of particles that are emitted from the nucleus |
Half-life | The decaying process of a radioisotope. The half-life of a radioisotope is the time it takes for one half a sample to decay |
Nuclear bombardment | Occurs when high-speed particles collide with a nucleus. Artificially creates radioisotopes. Stable nucleus → unstable nucleus |
Nuclear decay | When an atom emits a type of radiation. The breakdown of an unstable nucleus and the emittance of a radioactive particle. |
Nuclear fission | Occurs when a very heavy nucleus splits into two smaller nuclei |
Nuclear fusion | Occurs when two small nuclei combine to form a larger more stable nucleus, Tremendous amounts of energy are released after |
Chemical reaction | A process in which one or more substances are converted into new substances with different physical and chemical properties |
What is/are the unit of measurement for:
Mass: Grams (g),
Volume: cm^3, liters (L)
Length: meters (m)
Atom: amu
Density: g/cm^3, g/mL
JJ. Thomson: studied the flow of electric currents, discovered electrons, proposed that electrons were embedded within the atom. (w/out any organization)
"plum pudding model"
E. Rutherford: through his gold foil experiment, he proposed that protons are concentrated in a center called the nucleus. Electrons revolve in orbitals around nucleus
Bohr: the energy of each electron in an atom must be quantized. Each energy level (orbital) is given a quantum number, n. The lowest energy level (closest to nucleus) is called ground state, n=1. when an electron absorbs energy, it jumps to a higher energy level called excited state. When energy is released or emitted, the electron falls back to a lower energy level
Mendeleev: developed the early periodic table. organized elements by increasing atomic mass Arranged in a way so that the elements in the same column have similar properties
State all the postulates to Dalton’s atomic theory
Atoms can neither be divided nor destroyed.
All atoms of an element are identical.
Atoms of different elements differ.
Atoms of different elements combine in whole ratios to form compounds.
Chemical reactions consist of combination, rearrangement & separation of atoms.
Define physical and chemical changes and give 3 examples of each
Physical: Changes into the same kind of matter (melting, cutting, bending)
Chemical: Matter changes into a different kind of matter (chemical bonds are broken and cannot be restored), substance cannot be restored (burning, cooking, rust)
What are the 4 types of radioactive particles? Describe the properties of each.
Alpha (α)
High energy particles, represented as , does not have much penetrating power
Beta (β)
High speed electrons, represented as , 100 times more penetrating than alpha particles
Gamma (γ)
Very energetic form of light, represented as , most penetrating and harmful
Neutrons
, high penetrating (can pass through many materials), speed varies, can make objects radioactive, more penetrating than gamma radiation
Describe the Heisenberg uncertainty principle
The position of a moving object cannot simultaneously be measured and known exactly
What does the Pauli exclusion principle state about the spins of electrons?
A suborbital can only hold a maximum of 2 electrons and must have opposite spins ⇅
Early periodic table: elements organized by increasing atomic mass, arranged in a way so elements in the same column have similar properties
Todays periodic table: arranged according to periodic law, elements have a common number of valence electrons
Metals (located on the left of the staircase)
Good conductors of electricity
Solid at room temp (except mercury)
Malleable (sheets)
Ductile (fine wires)
Cations (+ charge)
Nonmetals (located on the rights side of the stair case)
Poor conductors of electricity
Gas, liquid, or solid at room temp
Anions (- charge)
Transition metals (located in the d-orbital, some in p, rectangle)
Not as reactive as other metals
Typically metallic properties
Good conductors
High luster
Metalloids (located on the staircase)
Semiconductors
Brittle solid at room temperature
Inner transition metals (located on f-region)
Less reactive than alkaline earth metals
Soft and slippery
Radioactive
Elements after uranium are artificial
List the main groups (families), of the periodic table and describe their unique properties
Alkali metals (group 1)
high ly reactive
Reacts w/water
Soft metal
Good conductors
Becomes plasma at high temperatures
Alkali earth metals (group 2)
Less reactive than group 1
Harder
Denser
Stronger
Higher melting point
Halogens (group 17)
Most reactive of non metals
Combien with most metals to form compounds
Halogen = salt former
Noble gases (group 18)
Not very reactive
Octet of electrons in outermost shell
Inner transition metals - Ianthanides
4f orbitals
Less reactive than alkaline earth metals
Soft, slipper
Inner transition metals - actides
Radioactive
Elements after uranium are artificial
Hydrogen
Family all on its own
Often resembles halogens
Very reactive bcs it only has one proton and one electron
Describe all the periodic trends discussed in class
Atomic radii (size of an atom) increases ↙
Ionization energy (the energy needed to remove an electron) increases ↗
Electron affinity/electronegativity (the ability of an atom to attract and hold an electron) increases ↗
Ionic Compounds | Covalent Compounds |
Metal + Metal | Nonmetal + Metal |
Use criss cross method | Don’t use criss cross method |
Valence electrons are transferred between elements | Valence electrons are shared |
High melting and boiling point | Low melting and boiling point |
Conducts electricity as a liquid | Does not conduct electricity as a liquid |
Soluble in water | Insoluble in water |
Hard, brittle |