Atomic Structure Ch4 Vocab

Nucleus

The center of an atom, containing protons and neutrons

Atom

Smallest particle of an element

Elements

Any substance that cannot be broken down into simpler substances

Proton

A subatomic particle with a positive charge found in the nucleus of an atom

Electron

A negatively charged subatomic particle that orbits the nucleus of an atom.

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Atomic Number

The number of protons in an atom

Isotopes

Atoms of the same element that have different numbers of neutrons

Energy Level

A region of an atom in which electrons of the same energy are likely to be found

Electron Cloud

A visual model of the most likely locations for the electrons in an atom

Orbital

A region of space around the nucleus where an electron is likely to be found, have different shapes

Electron Configuration

The arrangement of electrons in an atom

Ground State

The lowest energy state of an atom, closest to the nucleus

Dalton

A measure of mass for atoms and subatomic particles, same as the atomic mass unit

Mass number

The total number of protons and neutrons in the nucleus of an atom, always the number with the largest amount

Who is Democritus?

The first person to propose that matter was composed of tiny indivisible particles in 400 B.C.

What was John Dalton’s belief?

Atoms are a uniform, solid sphere

What were John Dalton’s four postulates?

1. Elements are composed of small indivisible particles called atoms.

2. Atoms of the same element are identical.  Atoms of different elements are different.

3. Atoms of different elements combine together in simple proportions to create a compound.

4. In a chemical reaction, atoms are rearranged, but not changed.

What did J.J. Thomson discover?

Electrons in an atom

What did Ernest Rutherford discover?

The nucleus, created the nucleus model

What was the significance of Niels Bohr?

Discovered energy levels, created the planetary model

What did Erwin Schrödinger do?

Found the electron cloud, an area where electrons are most likely to be found and created the Electron Cloud Model

What is important to know about element symbols?

• Contain ONE capital letter followed by lowercase letter(s) if necessary

• Ex, Co = Cobalt, CO = Carbon Monoxide

  • CO is a combination of Oxygen (O) and Carbon (C)

How do you find the amount of neutrons in an atom?

Mass number - Atomic number = Neutrons

Isotopes…

Determine the average atomic mass of an element.

How do you calculate the average atomic mass of an element?

(mass #)(# of atoms) + (mass #)(# of atoms) divided by the total # of atoms

• ex: if about 8 out of 10 chlorine atoms are chlorine-35 and 2 out of 10 are chlorine-37. then the aam is 35.4

Atoms emit light when…

Electrons move to a lower energy level

What is the maximum amount of electrons in each energy level?

1 - 2

2 - 8

3 - 18

4 - 32

5 - 50