1. Atoms and Elements

What is an atom?

Smallest unit of matter that still retains the properties of an element.

What unit of measurements are used for atoms, subatomic particles, molecules?

Dalton

Dalton is same as the atomic mass unit (amu)

How much do protons and neutrons weigh?

1.7 × 10^-24g

1 dalton

How much do electrons weigh?

1/2000 that of a neutron and proton,

so we can ignore electrons when atomic mass.

Name atomic models:

1. Bohr model (1913)

2. Electron cloud model, Schrodinger (1926)

Define element:

Any substance that cannot be broken down to any other substances by chemical reactions.

Define Compound:

Substance consisting of two or more fifferent elements combined in a fixed ratio.

Define isotopes:

Atoms with the same number of protons but a different number of neutrons.

How do isotopes of an element behave?

Identically the same in a chemical reaction.

Describe the process decay:

Nuclei do not have a tendency to lose subatomic particles.

Describe the 12C, 13C and 14C isotopes:

12C and 13C are stable.

14C is unstable, radioactive.

How does a radioactive isotope behave?

Nucleus decays spontaneously, giving off particles and energy.

When the radioactive decay leads to a change in the number of protons, it transforms the atom to an atom of a different element.

Radioactive isotopes have many useful applications in biology.

Describe atomic mass:

Average of the different isotope of the element.

Describe the process of radioactive decay:

In which a radioactive atom spontaneously gives off radiation in the form of energy or particles to reach a more stable state.

(Important to distinguish between radioactive material and the radiation it gives off.

Name and describe the 3 types of radioactive decay:

Alpha decay- Nucleus loses 2 protons.

Beta decay- Nucleus either loses or gains a proton.

Gamma decay- No change in proton number occurs, so the atom does not become a different elemnt.

Describe Valence:

Describe valence electrons:

Describe Valence shell: