Chemistry - Atom
neutron
one of three main particles that make up the atom. It is found in the nucleus and is neutral in electric charge. It has about the same mass and diameter as a proton.
proton
one of three main particles that make up the atom. It is found in the nucleus. It has an electrical charge of one +1 and a mass of 1 atomic mass unit (amu). Atoms of any given element have a unique number of protons that is different from the numbers of protons of all other elements.
average atomic mass
the weighted average of the atomic masses of the naturally occurring isotopes of an element
Fission
A nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy
Fusion
Creation of energy by joining the nuclei of two hydrogen atoms to form helium.
Radiation
Energy that is radiated or transmitted in the form of rays or waves or particles.
Dalton atomic theory
Proposed in 1804 All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed. Atoms of different elements can combine in simple whole number ratios to form chemical compounds. In chemical reactions, atoms are combined, separated, or rearranged
half-life
The time required for one half of the atoms of a radioisotope to emit radiation an decay products
beta particle
a high-speed electron with a 1- charge that is emitted during radioactive decay
alpha particle
a type of nuclear radiation consisting of two protons and two neutrons
gamma radiation
a type of nuclear radiation made of high-energy waves
electrons
are one of three main types of particles that make up the atom. They are extremely small and have an electric charge of -1. All atoms have the same number of electrons as protons.
isotope
atoms of the same element that differ in their numbers of neutrons
atom
comes from the Greek atomos and means "indivisible.
"plum pudding" model
consisted of a uniform sphere of positive charge with negative electrons embedded in the sphere. J.J. Thomson
atomic mass unit
is defined as a mass equal to one twelfth the mass of an atom of carbon-12.
mass number
is its mass in atomic mass units (amu), which is about equal to the total number of protons and neutrons in the atom. The number of neutrons = mass number - atomic number.
nucleus
positively charged center of an atom containing protons and neutrons.
The law of definite proportions
states that a given chemical compound always contains the same elements in the exact same proportions by mass.
The law of conservation of mass
states that matter cannot be created or destroyed.
The law of multiple proportions
states that whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.
atomic number
the number of protons in an atom. This is also unique for each element.
