1 Atomic Structure and Electron Configurations Free Online FlashCards

What does an atom’s atomic number identify?

The atomic number, $Z$, is the number of protons in an atom and determines its element.

How are mass number and neutron number related?

The mass number is the total number of protons and neutrons: $A = \text{protons} + \text{neutrons}$. Thus, neutrons equal $A-Z$.

What makes two atoms isotopes of the same element?

Isotopes are atoms of the same element with different numbers of neutrons. They have the same number of protons.

How is an ion’s net charge calculated?

An ion’s charge equals its number of protons minus its number of electrons: $\text{charge} = \text{protons} - \text{electrons}$.

What is a cation, and how does it form?

A cation is a positively charged ion formed when an atom loses electrons.

What does an orbital describe?

An orbital is a region of space where an electron is likely to be found, not a fixed path around the nucleus.

How many electrons can the $s$, $p$, $d$, and $f$ subshells hold?

The maximum capacities are $s: 2$, $p: 6$, $d: 10$, and $f: 14$ electrons.

What does the Aufbau principle state?

The Aufbau principle says electrons generally fill lower-energy orbitals before higher-energy orbitals.

What does Hund’s rule predict for equal-energy orbitals?

Hund’s rule states that electrons occupy equal-energy orbitals separately before pairing.

What spin relationship must two electrons in one orbital have?

The Pauli exclusion principle requires two electrons in the same orbital to have opposite spins.

What is oxygen’s ground-state electron configuration?

Oxygen has the ground-state configuration $1s^2\,2s^2\,2p^4$.

What is the ground-state electron configuration of chromium?

Chromium’s ground-state configuration is $[\mathrm{Ar}]\,3d^5\,4s^1$, rather than the simplest predicted $[\mathrm{Ar}]\,3d^4\,4s^2$.