CHE 121: Chapter 3 (Atoms & the Periodic Table)

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45 terms · Fundamentals of General Chemistry by McMurry

Atom

The smallest and simplest particle of an element.

Atomic Theory

A set of assumptions proposed by the English scientist John Dalton to explain the chemical behavior of matter.

Atomic Theory #1

All matter is composed of matter.

Atomic Theory #2

The atoms of a given element differ from the atoms of all other elements.

Atomic Theory #3

Chemical compounds consist of atoms combined in specific ratios.

Atomic Theory #4

Chemical reactions change only the way that atoms are combined in compounds. The atoms themselves are unchanged.

Subatomic Particle

Three kinds of fundamental particles from which atoms are made.

What are the 3 subatomic particles?

protons, neutrons, & electrons.

Proton

A positively charged subatomic particle.

Neutron

An electrically neutral subatomic particle.

Electron

A negatively charged subatomic particle.

Atomic Mass Unit (amu)

A convenient unit for describing the mass of an atom; 1 amu equals 1/12 the mass of a carbon-12 atom

Nucleus

The dense, central core of an atom that contains protons & neutrons.

Atomic Number "Z"

Atoms differ from one another according to the number of protons they contain.

Mass Number "A"

The sum of the protons and neutrons in an atom is called, _____?

Isotopes

Atoms with identical atomic numbers but different mass numbers.

Atomic Weight

The weighted average mass of an element's atoms.

Period

One of the 7 horizontal rows of elements in the periodic table.

Group

One of the 18 vertical columns of elements in the periodic table.

Main Group Elements

An element in one of the two groups on the left or the six groups on the right of the periodic table.

Transition Metal Element

An element in one of the 10 smaller groups near the middle of the periodic table.

Inner Transition Metal Element

An element in one of the 14 groups shown separately at the bottom of the periodic table.

Alkali Metal

An element in group 1A of the periodic table.

Alkaline Earth Metal

An element in group 2A of the periodic table.

Halogen

An element in group 7A of the periodic table.

Noble Gas

An element in group 8A of the periodic table.

Shell (electron)

A grouping of electrons in an atom according to energy.

Subshell (Electron)

A grouping of electrons in a shell according to the shape of the region of space they occupy.

Orbital

A region of space within an atom where an electron in a given subshell can be found.

How many orbitals in subshell "s"?

1

How many electrons per orbital?

2 moving in opposite directions

How many orbitals in subshell "p"?

3

How many orbitals in subshell "d"?

5

How many orbitals in subshell "f"?

7

Electron Configuration

The specific arrangement of electrons in an atom's shells and subshells.

EC Rule #1

Electrons occupy the lowest energy orbitals available, beginning with 1s

EC Rule #2

Each orbital can hold only two electrons, which must be of opposite spin.

EC Rule #3

Two or more orbitals with the same energy-- the three "p" orbitals or the five "d" orbitals--- are each half filled before any one orbital is completely filled by addition of the second electron.

s-Block Element

A main group element that results from the filling of an s orbital.

p-Block Element

A main group element that results from the filling of p orbitals.

d-Block Element

A transition metal element that results from the filling of d orbitals.

f-Block Element

An inner transition metal element that results from the filling of f orbitals

Valence Shell

The outermost electron shell of an atom.

Valence Electron

An electron in the valence shell of an atom.

Electron-dot Symbol

An atomic symbol with dots placed around it to indicate the number of valence electrons.

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