Atomic Structure (notes, review ws)

Who first described/discovered: The atom?

Democritus

Who first described/discovered: Electrons?

Thomson

Who first described/discovered: Plum pudding model?

Thomson

Who first described/discovered: Protons?

Goldstein

Who first described/discovered: Neutrons?

Chadwick

Who first described/discovered: Nuclear atom?

Rutherford

Location, Charge, and Mass(amu) of a proton?

Location: nucleus

Charge: +

Mass (amu): 1 amu

Location, charge, and mass (amu) of a neutron?

Location: nucleus

Charge: 0

Mass (amu): 1 amu

Location, charge, and mass(amu) of a electron?

Location: outside nucleus (orbits)

Charge: -

Mass(amu): 0 amu

An experiment in which Rutherford fired alpha particles at thin gold foil to study the structure of the atom. Most particles passed through, but a few were deflected, showing that atoms are mostly empty space with a small, dense, positively charged nucleus

Gold Foil Experiment

Thomson’s Atom

Rutherford’s Atom

How did Rutherford’s Gold Foil Experiment prove Thomson’s model incorrect?

Thomson’s model said positive charge was spread evenly throughout the atom, so alpha particles should pass through with little or no deflection. Rutherford found that some particles were strongly deflected, proving that positive charge and most of the mass are concentrated in a small, dense nucleus

Atom to molecules ratio:

100,000:1

The number of protons is the:

Atomic number

ex: Iodine’s atomic # is 53 (on P.T.)

The total number of protons + neutrons (for 1 particular atom) is the:

Mass number

Atoms with the same number of protons, but a different number of neutrons is an:

Isotope

The average weighted mass of all isotopes of an element is the:

Atomic mass (calculated the same as average atomic mass)

The basic building block of all matter in the universe is an:

Atom

What are the three isotopes of hydrogen?

Protium: 1 proton, 0 neutrons

Deuterium: 1 proton, 1 neutron

Tritium: 1 proton, 2 neutrons

What are the three most common isotopes of carbon?

C-12: 6 protons, 6 neutrons

C-13: 6 protons, 7 neutrons

C-14: 6 protons, 8 neutrons

Atoms that have a charge (atoms that have gained or lost an electron) (protons and electrons are different) is an:

Ion

What determines the identity of an atom?

The number of protons

Why does the nucleus have such a high density?

It contains almost all of an atoms mass in an extremely tiny space