Chemistry Midterm Review

lewis structure

(also known as Lewis dot diagrams, Lewis dot formulas, Lewis dot structures, and electron dot structures) are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule.

superscript

(of a letter, figure, or symbol) written or printed above the line.

subscript

(of a letter, figure, or symbol) written or printed below the line.

15,500 grams equals

15.5 kg

transition metals

38 elements in groups 3 through 12 of the periodic table are called "transition metals". As with all metals, the transition elements are both ductile and malleable, and conduct electricity and heat. The interesting thing about transition metals is that their valence electrons, or the electrons they use to combine with other elements, are present in more than one shell. This is the reason why they often exhibit several common oxidation states. There are three noteworthy elements in the transition metals family. These elements are iron, cobalt, and nickel, and they are the only elements known to produce a magnetic field.

chemical bonds

A chemical bond is a lasting attraction between atoms that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between atoms with opposite charges, or through the sharing of electrons as in the covalent bonds.

chemical change vs physical change

A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.

Al

Aluminum

Sb

Antimony

Ca

Calcium

Cs

Cesium

Co

Cobalt

Cu

Copper

mendeleev

Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He formulated the Periodic Law, created a farsighted version of the periodic table of elements

electron dot structure

Electron dot structure - valence electrons are represented by dots placed around the chemical symbol. Electrons are placed up to two on each side of the elemental symbol for a maximum of eight, which is the number of electrons in a filled s and p shell.

d sublevel

Electrons can not just exist at any distance from the nucleus. These orbits are called levels and we number them 1, 2, 3, 4, and so forth with the 1st level being the orbit closest to the nucleus. The levels can be broken down into sublevels. We have s, p, d, and f sublevels. Level one has one sublevel - an s. Level 2 has 2 sublevels - s and p. Level 3 has 3 sublevels - s, p, and d. Level 4 has 4 sublevels - s, p, d, and f.

diatomic molecule

If the diatomic molecule consists of atoms from two different elements, then it is a heteronuclear diatomic molecule. There are seven elements that naturally occur as homonuclear diatomic molecules in their gaseous states: hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine.

Ir

Iridium

Fe

Iron

Pb

Lead

Mg

Magnesium

Mn

Manganese

Hg

Mercury

Ni

Nickel

K

Potassium

s, p, d, f sublevels

Principle Quantum # = n. # sublevels. Sublevel. Orbital. Electron Capacity. 1. 1. s. s. 1. 1 x 2 = 2e. 2. 2. s p. p. 3. 3 x 2 = 6e. 3. 3. s p d. d. 5. 5 x 2 = 10e. 4. 4. s p d f.

Ra

Radium

kelvin

SI base unit of thermodynamic temperature, equal in magnitude to the degree Celsius....commonly used in determining temps in chemistry.

Ag

Silver

Na

Sodium

isotopic notation

Subscripts and superscripts can be added to an element's symbol to specify a particular isotope of the element and provide other important information. ... Because all of the isotopes of an element have the same atomic number, the atomic number is often left off the isotope notation

nonmetals

The Non-Metal elements are: Hydrogen. Carbon. Nitrogen. Oxygen. Phosphorus. Sulfur. Selenium.

monatomic element

The only chemical elements which are stable single atom molecules at standard temperature and pressure (STP) are the noble gases. These are helium, neon, argon, krypton, xenon and radon. The heavier noble gases can form chemical compounds, but the lighter ones are non-reactive or inert.

electronegativity

a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.

quantum numbers

a number that occurs in the theoretical expression for the value of some quantized property of a subatomic particle, atom, or molecule and can only have certain integral or half-integral values.

azimuthal quantum number

a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital.

chemical formula

a set of chemical symbols showing the elements present in a compound and their relative proportions, and in some cases the structure of the compound.

mixture

a substance made by mixing other substances together. "form the mixture into a manageable dough"

entropy

a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.

compound

a thing that is composed of two or more separate elements; a mixture. "the air smelled like a compound of diesel and gasoline fumes"

evaporation

a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance....think of when you see the steam from a chemical plant....you can only see it until a certain point in the air....after that it's not visible...it has evaporated.

diatomic element

all gases, and they form molecules because they don't have full valence shells on their own. The diatomic elements are: Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, and Fluorine. Ways to remember them are: I Had Burritos From Cleaveland -NO!

ion

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

metalloids

an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. They are electrical semiconductors. The Metalloids are: Boron Silicon Germanium Arsenic Antimony Tellurium Polonium

plasma

an ionized gas consisting of positive ions and free electrons (as in the upper atmosphere and in fluorescent lamps) or at very high temperatures (as in stars and nuclear fusion reactors)...very high kinetic energy.

chemical property

any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.

halogens

are five non-metallic elements found in group 17 of the periodic table. The term "halogen" means "salt-former" and compounds containing halogens are called "salts". All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1. The halogens exist, at room temperature, in all three states of matter: Solid- Iodine, Astatine Liquid- Bromine Gas- Fluorine, Chlorine The Halogens are: Fluorine Chlorine Bromine Iodine Astatine

fahrenheit

conforming to a thermometric scale on which under standard atmospheric pressure the boiling point of water is at 212 degrees above the zero of the scale, the freezing point is at 32 degrees above zero....what we use in day to day temps.

matter

defined as anything that has mass (an amount of matter in an object) and occupies space (which is measured as volume).

qualitative data

descriptive data

significant digits

each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first nonzero digit. "this text will round numbers to three significant figures"

isotope

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

kinetic energy

energy that a body possesses by virtue of being in motion.

pure substances

has a definite and constant composition — like salt or sugar. A pure substance can be either an element or a compound, but the composition of a pure substance doesn't vary.

electron configuration

he distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom is 1s2 2s2 2p6.

orbital notation

he orbital notation uses only the n and ℓℓ quantum numbers. In this notation we simply state the principle quantum number nn as a number. A letter is used to denote the ℓℓ term as letters s,p,d... So let's imagine a hydrogen atom in its lowest energy state. This is the ground state. The electron wavefunction is then described by n=1, ℓℓ = 0, and mℓmℓ=0.

quantitative

information about quantities; that is, information that can be measured and written down with numbers.

heterogeneous mixture

made of different substances that remain physically separate. Heterogeneous mixtures always have more than one phase (regions with uniform composition and properties). A mixture of sand and sugar is a heterogeneous mixture.

orbitals

n atomic orbital is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus.

celsius

of or denoting a scale of temperature in which water freezes at 0° and boils at 100° under standard conditions...commonly used in determining temps in chemistry and petrochemical industries.

homogeneous

of the same kind; alike.

density formula

p=m/V, or density (p) is equal to mass (m) divided by volume (V). The calculator can use any two of the values to calculate the third. Density is defined as mass per unit volume.

hypothesis

proposed explanation made on the basis of limited evidence as a starting point for further investigation.

noble gases

six noble gases are found in group 18 of the periodic table. These elements were considered to be inert gases until the 1960's, because their oxidation number of 0 prevents the noble gases from forming compounds readily. All noble gases have the maximum number of electrons possible in their outer shell (2 for Helium, 8 for all others), making them stable. Helium Neon Argon Krypton Xenon Radon

organic chemistry

study of carbon compounds....carbon is the backbone of many many things

nuclear chemistry

study of radioactive substances... nuclear = radioactive

biochemistry

study of the chemical process in living things.... bio = life

inorganic chemistry

study of things that aren't carbon... Inorganic...In = without

atomic mass

the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.

ionization

the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjunction with other chemical changes.

mass number

the total number of protons and neutrons in a nucleus.

sublimation

the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase....basically goes from a solid to gas in a way that it "disappears"

enthalpy

thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume. the change in enthalpy associated with a particular chemical process.

condensation

water that collects as droplets on a cold surface when humid air is in contact with it....think of your windows when the a/c is on in the house, but it's humid outside.