2011 Science Vocabulary Ch. 2,5

uncharged particles in the nucleus

electrically neutral particle that is present in the nucleus of all atoms

has the same mass as a proton

The positively charged central part of the atom

Negatively charged particles

part of the atom in which electrons move

The positively charged particles in the nucleus

Tells you how heavy an element's atoms are compared with atoms of other elements

Tells you the number of protons in the nucleus of each atom of an element

a material that cannot be broken down to simpler substances by ordinary mean

States that a given compound is always made of the same elements in the same proportion by mass

A pure substance whose smallest unit is made up of atoms of more than one elemnt

A sample of matter that has the same composition and proporties throughout

The sum of an atom's protons and neutrons

states that matter is neither created nor destroyed, only changed in form

A small particle that makes up most types of matter

Anything that had mass and takes up space

Formed when two or more substances come together but don't combine to form a new, pure substance

Atoms of the same element that have different numbers of neutrons

positively charged, heavy particle contained in the nucleus of all atoms

Particle in the nucleus of an atom that carries a positive charge

Number of protons in the nucleus of an atom of a specific element

Whole number that tells how many protons are in the nucleus of each atom of an element

Time needed for one-half the mass of a sample of a radioactive isotope to decay

Can vary from fractions of a second to billions of years

Number of neutrons plus the number of protons in the nucleus of an atom

Substance that cannot be broken down into simpler substances and whose atoms are exactly alike

tiny negatively chargd particle that is present in all atoms and that has almost no mass

Region surrounding the nucleus of an atom, where electrons are more likely to be found

atoms of the same element that have different numbers of neutrons in their nuclei

Two or more atoms of the same element that have different numbers of neutrons

Release of nuclear particles and energy from unstable atomic nucleu