Chapter 9 Review-The Atom

Atoms of the same element that have different numbers of neutrons.

Sum of the number of protons and neutrons in an atom.

The average mass of an element's isotopes, weighted according to the abundance of each isotope.

An alpha particle consists of two protons and two neutrons.

Elements that spontaneously emit radiation.

When atoms release particles of radiation, they change to different elements.

Smallest piece of an element that still represents that element.

An atomic particle with one negative charge.

Who performed experiments showing that most of an atom's mass is concentrated in its center?

An atom that is no longer neutral because it has gained or lost electrons.

An ion that has a negative charge is formed when an atom

Who discovered the neutron?

An ion that has a positive charge is formed when an atom

An area around an atomic nucleus where an electron is most likely to be located.

There are 6 types of quarks.

An atomic particle that has one positive charge.

How do you find the mass number is an atom?

The number of protons in an atom of an element.

Area in the center of the atom where most of an atom's mass and (+) charge is concentrated.

Which person first used the term "radioactive"?

The neutral particle in the nucleus of an atom.

What is happening if a neutron changes into a proton and a high energy electron is emitted?

An electron cloud is mostly empty space.

Occurs when an unstable nucleus changes into another more stable nucleus by emitting radiation.

Who devised the "plum pudding model" in atomic theory?