What is an atom?
The smallest particle that retains the chemical properties of its substance.
What are the three subatomic particles?
Protons, neutrons, and electrons.
Where are protons and neutrons found in an atom?
In the nucleus at the center of the atom.
Where are electrons found in an atom?
Orbiting around the nucleus in electron shells.
What is the charge of a proton?
Positive.
What is the charge of a neutron?
No charge — it is neutral.
What is the charge of an electron?
Negative.
Why is a typical atom electrically neutral?
Because the number of electrons equals the number of protons, balancing the negative and positive charges.
What is the atomic number of an element?
The number of protons in the nucleus of its atoms.
Why do electrons determine the chemical behavior of an atom?
Because they are the subatomic particles that interact with other atoms — protons and neutrons are locked in the nucleus.
What is potential energy in the context of electrons?
The energy of position that holds electrons in orbit — electrons farther from the nucleus have greater potential energy.
What is an electron shell?
An energy level around the nucleus where electrons orbit; most shells hold up to eight electrons.
Why do atoms undergo chemical reactions?
To fill their outermost electron shell by gaining, losing, or sharing electrons.
What is an ion?
An atom that has gained or lost one or more electrons, giving it an electrical charge.
What is a cation?
A positively charged ion formed when an atom loses one or more electrons.
What is an anion?
A negatively charged ion formed when an atom gains one or more electrons.
What are isotopes?
Atoms of the same element that have the same number of protons but different numbers of neutrons.
Do isotopes of the same element share the same chemical properties?
Yes — because they have the same number of protons and electrons, their chemical behavior is identical.
What is radioactive decay?
The process by which an unstable isotope breaks up into atoms of other elements.
What is a molecule?
A group of atoms held together by chemical bonds.
What is a chemical bond?
The energy or force holding two atoms together in a molecule.
What are the three main types of chemical bonds?
Ionic bonds, covalent bonds, and hydrogen bonds.
What is an ionic bond?
A bond formed by the attraction between oppositely charged ions.
Why does table salt form crystals?
Because ionic bonds are nondirectional — each ion attracts all surrounding ions of opposite charge — forming an elaborate alternating matrix.
