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48 Cd Cadmium 112.4144

Cadmium

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

Cadmium is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it prefers oxidation state +2 in most of its compounds and like mercury it shows a low melting point compared to transition metals.

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Quick Facts

Atomic Number 48
Period 5
Group 12
Phase Solid
Appearance silvery bluish-gray metallic
About Transition Metals

Transition metals are elements with partially filled d-orbitals. They are hard, have high melting points, and often form colored compounds.

History

Discovered By Karl Samuel Leberecht Hermann
Named By Isotopes of cadmium

Physical Properties

Atomic Mass 112.4144
Density 8.65 g/L
Molar Heat 26.02 J/(mol·K)
Phase Transition (Melting & Boiling Points)

Cadmium melts at 594.22 K and boils at 1040 K.

Atomic Properties

Electron Config [Kr] 4d10 5s2
Electronegativity 1.69
Electron Affinity -68 kJ/mol
Ionization Energy 867.8 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.

Photograph

Image of Cadmium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

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.