Chemistry Unit 3.1 & 3.2

3.1 and 3.2 quiz

Protons

positively charged particle; located in the nucleus

Neutrons

neutral/no charge; located in the nucleus

Electrons

negatively charged; located outside the nucleus in energy levels

Mass Number

Protons + Neutrons

Net Charge

Protons + Electrons

Atomic Number

the number of protons

Isotopes

an atom of an element with a different number of neutrons in the nucleus

• protons and electrons remain the same

Atom

has a neutral charge

Ion

Has a positive or negative charge

• unequal amount of protons/electrons

Atomic Weight

The average weight of an element with respect to all its isotopes and their abundances

• under the atomic symbol

Marie Curie

Coined the term radioactivity:

• the spontaneous disintegration of elements into smaller pieces by the emission of particles or rays

Nuclear Fission

The nuclear reaction that splits a heavy nucleus into two

• releases larges amounts of energy

  • used in power plants

Nuclear Fusion

The nuclear reaction where two or more smaller nuclei combine to form a single, large nucleus

• releases a large amount of energy

  • occurs in the sun or stars

Alpha Decay

When an alpha particle is emitted by a radioactive isotope

• consists of 2 protons and 2 electrons

  • helium nucleus (4 2 He)

  • positively charged

Beta Decay

An electron is emitted from the radioactive nucleus

• no mass and -1 charge

• a neutron becomes a proton

Half-Life

The amount of time needed for one half of a quantity of a substance to undergo a change

• equation: N=N₀x(1/2)^t/t_1/2

N=final amount, N₀=initial time, t=time, t_1/2=half-life