Unit 2 chemistry terms

Chemical potential energy

A type of potential energy due to energy stored in the bonds of chemicals or molecules.

Closed system

A system that only exchanges energy with its surroundings; it does not exchange matter

Energy

The capacity to do work

Force

A push or pull that can change the motion of an object

Gas

A phase of matter without a definite volume or shape; it can spread out and fill any space

Gravitational potential energy

A type of potential energy that results from the earth gravity

Gravity

The natural force of attraction between two objects with mass which tends to pull them together. Near the Earth surface this force tends to pull objects towards the Earth center.

heat energy

The energy due to the motion of the atoms or molecules within a system

isolated system

A system that does not take in or release energy or matter

joule

The SI unit for energy

Kinetic energy

The energy of motion which depends on temperature

Law of conservation of energy

A law stating that energy cannot be created or destroy; it can only change forms

law of conservation of matter

A law stating that matter cannot be created or destroyed in chemical reaction; it can only be rearranged

Liquid

A phase of matter that has a fixed volume, but lack of fixed shape

Open system

A system that takes in or releases both energy and matter

Phase

A distinct form of matter such as solid liquid or gas

phase change

A physical change from one form to another, such as from solid to liquid

plasma

A phase of matter where whole atoms separate into smaller pieces. Plasma is typically in the form of hot, gas like clouds, such as those that make up the sun and other stars

potential energy

The energy an object has due to its composition or its position relative to a force

Solid

A phase of matter that has a fixed shape and volume

SI

International system of units or the metric system

System

A group of connected and related things

temperature

The measure of the kinetic energy in a system

Unit

A term of measurement in math that describes what a number stands for

Volume

The space occupied by matter

non matter

ex. feelings, forces, and energy

matter

anything that takes up space and has mass

Albert Einstein

Scientist known for his theory of relativity. Explained photoelectric effect and created quantum mechanics.

Atomic number.

The number of protons in an atom's nucleus, symbolized by Z.

Average atomic mass.

The average atomic mass is the average of the atomic masses of each of an element's isotopes, weighted by their natural abundance.

battery

A group of electrochemical cells that are arranged in a series and continuously convert chemical energy into electrical energy

bohr model

A model of an atom proposed by bohr in 1900s. Negatively charged electrons were thought to move an orbit around the nucleus equally spaced apart from each other and the nucleus.

cathode ray

Stream of electrons emitted by the cathode in a vacuum tube

Charge

A property of matter that causes it to experience electrical forces

Chemical reaction

A process in which substances are converted into new ones with a different properties

Chemical symbol

Abbreviation for the name of a chemical element; it consist of a single capital letter or capital letter followed by a small letter

Dmitri Mendeleev

A Russian chemist to developed a periodic table of elements

Electron

A negatively charged subatomic particle, located outside the nucleus of an atom

electron cloud

The area around the nucleus where electrons are most likely to be located

Ernest Rutherford

A British physicist who discovered the atomic nucleus. He also discovered that atoms are made of mostly empty space.

Gas phase

The physical state in which a substance has no fixed shape or volume

Ion

A charge species that results from the gain or loss of electrons from a neutral atom or molecule

isotope

An atom of an element having a specific number of neutrons in the nucleus

J.J. Thompson

A British physicist credited for the discovery of the electron and of isotopes

mass number

The total number of protons and neutrons in an atom ; it is symbolized by A

molecule

A covalently bonded group of atoms

Negatively charged

Containing a negative electrical charge, due to having more electrons than protons

Neutral

No charge

neutron

An uncharged subatomic particle in the nucleus

Niels Bohr

created the Bohr model. Contributed to understanding atomic structure and quantum mechanics.

nucleus

The center of mass and the positive charge of an atom

periodic table

A table that shows the elements and their atomic number, symbol, and average atomic mass. Elements with similar chemical properties are grouped together.

photoelectric effect

A phenomenon in which electrons are ejected from the surface of a metal when light shines on the metal

Photon

A packet of light energy technically called a quantum of electromagnetic radiation

plum-pudding model

an atomic model proposed by Thompson in the late 1800s but not held as true today. Negatively charged electrons were thought to be scattered in a positively charged substance.

positively charged

Containing a positive electrical charge due to having more protons than electrons

Proton

A positively charged subatomic particle located in the nucleus

Quantum mechanic

A theory that explains the behavior of matter and energy on the atomic scale

Robert Millikan

an American experimental physicist known for measuring the charge on the electron and for his work on the photoelectric effect. did the voltage and oil experiment.

voltage

The force that causes electrical current to flow

actinides

Rare earth metals of Period 7 of the periodic table. Actinides are characterized as silvery colored, great conductors of electricity, and radioactive.

alkaline metals

Highly reactive metals from group 1, such as lithium, sodium, and potassium

alkaline earth metals

Group 2 elements of the periodic table. Alkaline earths metals are characterized as silvery, hard, dense, and reactive, and usually have an oxidation number of +2.

conductive

Able to pass heat, electric electricity, or sound.

Core electrons

The electrons in the atom that do not participate in bonding

Family

Elements on the periodic table that are generally grouped together. All elements in a family have similar properties.

Full octet

A full valence shell, usually consisting of 8 electrons

Group

A column of elements in the periodic table, labeled by number a letter. A group is also known as a family. Elements in a group have similar properties.

halogens

Group 17 elements of the periodic table. They are characterized as highly reactive, diatomic nonmetals.

Lanthanides

Rare earth metals period 6 of the periodic table. Lanthanides are characterized as silvery colored and as good conductors of electricity.

malleable

A property of matter that means it can be reformed into a different shape without breaking

Metal

An element that is shiny, solid, and a good conductor, is malleable, and has a high melting point.

metalloid

An element that has some properties characteristics of metals and some of nonmetals

Noble gases

Elements from group 18 (the column on the far right hand side of the periodic table), whose electrons have closed shells. Group 18 elements have a stable electron configuration, which makes them relatively unreactive. Helium has a full outer shell with two electrons. The other noble gases have eight valence electrons(an octet).

Nonmetal

An element that does not demonstrate the classic properties of a metal

period

A row of elements in the periodic table, labeled by atomic number. Elements in a period have the same number of core electrons, but different chemical properties.

prediction

A statement explaining that if the hypothesis is true, then observations that agree with the hypothesis will be made in an experiment.

radioactive

Containing atoms with nuclei that spontaneously change

Reactive

Having a tendency to react chemically

representative elements

Normal or typical elements found on the far left and right ends of the periodic table, excluding the middle columns of groups 3 through 12 and group 18

transition metal

Elements in groups 3 to 12 of the periodic table. Transition metals are characterized as very hard and usually shiny and are excellent conductors, with high melting and boiling points.

valence electron

An electron on the outer layer of an atom; valence electrons are usually involved in bonding.