19 K Potassium 39.09831

Potassium

ALKALI METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.

Potassium is a chemical element with symbol K (derived from Neo-Latin, kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name is derived. In the Periodic table, potassium is one of seven elements in column (group) 1 (alkali metals):they all have a single valence electron in their outer electron shell, which they readily give up to create an atom with a positive charge - a cation, and combine with anions to form salts.

Quick Facts

Atomic Number 19
Period 4
Group 1
Phase Solid
Appearance silvery gray
About Alkali Metals

Alkali metals are highly reactive, soft, silver, and shiny metals found in Group 1. They readily lose their outermost electron to form positive ions (cations) with a charge of +1.

History

Discovered By Humphry Davy
Named By Unknown

Physical Properties

Atomic Mass 39.09831
Density 0.862 g/L
Molar Heat 29.6 J/(mol·K)
Phase Transition (Melting & Boiling Points)

Potassium melts at 336.7 K and boils at 1032 K.

Atomic Properties

Electron Config [Ar] 4s1
Electronegativity 0.82
Electron Affinity 48.383 kJ/mol
Ionization Energy 418.8 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.
Emission Spectrum Emission spectrum of Potassium

Photograph

Image of Potassium Source: Wikipedia

External Resources

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.