Honors Chemistry - Chapter 3

Atom

Smallest piece of an element that has all of the properties of that element

Nucleus

The central location of atoms, with protons and neutrons

Proton

• 1 amu

• 2nd discovered

• positive charge

Neutron

• 1 amu

• 3rd discovered

• no charge

Electron

• 0 amu

• 1st discovered

• negative charge

Atomic number

# of protons in the nucleus of an atom

Atomic mass

# of protons and neutrons in the nucleus of an atom

Isotope

Atoms of the same element having different atomic masses

Ion

Atoms of the same element having different amounts of electrons (have charges)

Democritus 

• greek philosopher

• believed that the universe was made of tiny uncuttable pieces

• atomos → not to be cut, referring to the smallest piece of matter

John Dalton postulates

• all matter is made of extremely small particles called atoms

• atoms of the same element are alike in mass and size

• atoms of different elements have different masses and sizes

• atoms cannot be subdivided, created, or destroyed

• atoms combine to form compounds in simple numerical ratios

• in chemical reactions, atoms are combined, separated, or destroyed

What does Dalton’s hard sphere model look like

A pool ball

What were JJ Thomsons conclusions from the cathode ray tube experiement

• the electron is negatively charged

• atoms can be divided

What did Thomsons plum pudding model look like and how does it differ from Daltons model

• a chocolate chip cookie

• it has electrons throughout  positive base instead of all one thing

What did Robert Millikan discover form the oil drop experiment

the mass and charge of the electron

What are Ernest Rutherfords conclusions from the gold foil experiment

• the atom is mostly empty space

• most of the atoms mass is in the nucleus

• the proton is positively charged

What did Rutherfords empty space or nuclear model look like and how does it differ from thomsons model

• a cherry

• the positive charge is only present in the middle instead of all throughout the atom

what did the Bohr model or planetary space model look like and how is it different form Rutherfords model

• the solar system

• the electrons orbit around the nucleus instead of staying put

What did the quantum mechanical model look like and how is it different from Bohrs model

the electrons don’t orbit in definite paths, not fixed orbits

Law of multiple proportions

Atoms of two or more elements can combine in different ratios to form more than one compound

Law of conservation of mass

Total mass or reactants in any chemical reaction is exactly equal to the total mass of the products

Law of definite composition/proportion

A compound always contains two or more elements combined in definite proportions by mass

What particles belon in the nucleus of an atom

Protons and neutrons

What particles go in the orbitals or shells of an atom

Electrons

Which particles have mass

Neutrons and protons

What subatomic particles influence the average atomic mass

Protons and neutrons