atoms and elements study guide

What is the definition of an atom?

The smallest part of a substance that cannot be broken down chemically.

What is located at the nucleus of an atom?

Protons and neutrons.

What causes bright-line spectra?

Electrons transition from higher-energy orbits to lower-energy orbits.

What does the Lyman series represent?

Transitions back to the n=1 orbit, high energy, UV.

Which quantum number indicates the shape of an orbital?

l (angular momentum quantum number).

What does the Aufbau principle state?

Electrons fill the lowest energy orbitals first.

What is Hund's rule?

Every orbital in a subshell must have one electron before any can have two.

What is the Pauli exclusion principle?

No two electrons in an atom can have the same set of four quantum numbers.

What is the octet rule?

Atoms tend to have 8 valence electrons in their outer shell.

What is noble gas configuration in electron configuration?

Using the elemental symbol of the last noble gas prior, followed by the configuration of remaining electrons.

What do transition metals exhibit?

A range of oxidation states.

What is the common characteristic of alkali metals?

They have one valence electron and typically form +1 charge ions.

Why do halogens have high electron affinities?

They are reactive nonmetals with seven valence electrons.

How does atomic radius change in the periodic table?

Atomic radius increases from top to bottom and right to left.

How does ionization energy vary in the periodic table?

Ionization energy increases from bottom to top and left to right.

What is electronegativity?

The tendency of an atom to attract electrons, higher values indicate greater attraction.

What occurs in the excited state of an electron?

A valence electron absorbs energy and jumps to a higher energy level.

What is unique about isoelectronic atoms?

They have the same electron configuration, whether as ions or neutral atoms.