Chemistry Unit 1

Textbook chapters: 1, 2, 3, 4, 19

Element Symbols

abbreviations for the chemical elements

Law of Constant Composition

A given compound always has the same composition regardless of where it comes from

Dalton's atomic theory

1. elements are made of atoms

2. all atoms of a given element are identical

3. atoms of one element combine with atoms of other elements toform compounds, which have the same relative numbers and types of atoms

4. atoms are not created or destroyed, chemical reactions change the grouping of atoms

Atom

Basic unit of matter

Compound

Substance made of atoms of two or more elements, always contains the same relative mass of elements

Chemical Formula

expresses types of atoms and number of each type in each molecule of a compound

Electron

A subatomic particle that has a negative charge (outside of nucleus)

Nuclear Atom

atom with a dense center of positive charge

Nucleus

Dense center of an atom

Proton

positively charged particle in the nucleus of an atom

Neutron

neutral charged particle (no charge) in the nucleus of an atom

Isotopes

atom of the same element with different mass number (different number of neutrons)

Atomic number (Z)

The number of protons in an atom, determines which element it is

Mass number (A)

The total number of neutrons and protons in an atom

Periodic Table

Shows all known elements and information about each

Group

Family of elements with similar characteristics

Alkali Metals

any metal in Group 1A of the periodic table

Alkaline earth metals

metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive

Halogens

Group 7A

Noble Gases

the elements in Group 8A of the periodic table, don't usually combine with atoms of the same element

Noble metals

relatively nonreactive (gold, silver, platinum) found nearly pure in natural environments

Transition metals

elements that form a bridge between elements on the left and right sides of the periodic table

Metals

1. efficient conduction of heat/electricity

2. malleability

3. ductility

4. lustrous (shiny appearance)

Nonmetals

small number of elements, metals properties (most are gaseous at room temp.)

Metalloids

Elements that have properties of both metals and nonmetals (close to stair-step line)

Diatomic molecule

Molecule made of two of the same element (nitrogen gas, oxygen gas)

Allotrope

Different structural form of the same element

Ion

adding or removing an electron from a neutral atom

Cation

ion with a positive charge

Anion

atom with a negative charge

Ionic Compound

Compound forms between metal and nonmetal, must have a net charge of zero

J.J Thompson's experiments

atoms have tiny negative charged particles (electrons)

Plum pudding model

electrons are suspended in a positively charged cloud

Rutherford's experiments

Atoms have a positively charged nucleus

Metals tend to…

lose electrons to form positive ions (cations)

Nonmetals tend to…

gain electrons to form negative ion (anion) and are named using the root of the atom + ide

Nuclide

general term for any isotope of any element

Radioactive

Nucleus SPONTANEOUSLY decompose

Band of stability

Reflects proton to neutron ratio in stable atomic nuclei

Elements that are radioactive

Have an atomic number greater than 83 (Bismuth)

Radioactive decay

spontaneous break down of an isotope's unstable atomic nucleus and other particles/energy

Beta particle

Electron emitted in decay

Nuclear equation

Atomic mass and mass number are conserved

Alpha particle

Helium nucleus

Alpha particle production

Happens with heavy radioactive nuclides

Beta particle production

Turns a neutron into a proton

Gamma ray

the high-energy photon emitted by a nucleus during fission and radioactive decay

Positron

particle with the same mass as an electron, but has a positive charge

Positron production

Turns a proton into a neutron

Electron capture

inner-orbital electrons is captured by the nucleus

Decay series

occurs until a stable nuclide is formed

Nuclear transformation

change of one element to another

transuranium elements

elements with atomic numbers greater than 92, made by man

Geiger-Muller counter (Geiger counter)

an instrument that measures the rate of radioactive decay based on the ions and electrons produced as a radioactive particle passes through a gas-filled chamber

Scintillation counter

Gives off light when struck by a high energy particle

Half-life

length of time required for half of the radioactive atoms in a sample to decay

Radiocarbon/Carbon-14 dating

method for determining age by comparing the amount of carbon-14 to the amount of carbon-12 in a sample

Radiotracers

radioactive nuclides introduced into organisms and subsequently tracked throughout the organism

Fusion

Combines two lighter nuclei to form a heavier nucleus, expels a lot of energy

Fission

Splitting apart a heavy nuclide by firing a neutron at high speed

Chain reactions

Occurs when the fission on one atom causes the fission of other atoms

Critical mass

certain mass of fissionable material is needed to achieve critical state

Breeder reactors

Fissionable fuel is produced while the while the reactor runs

Rem

Indicates the danger radiation poses to humans