Californium

ACTINIDE

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

Californium is a radioactive metallic chemical element with symbol Cf and atomic number 98. The element was first made in 1950 at the University of California Radiation Laboratory in Berkeley, by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium).

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Quick Facts

Atomic Number 98

Period 7

Group 12

Phase Solid

Appearance silvery

About Actinides

Actinides are the 15 metallic elements with atomic numbers 89–103. All actinides are radioactive.

History

Discovered By Lawrence Berkeley National Laboratory

Named By Unknown

Physical Properties

Atomic Mass 251

Density 15.1 g/L

Molar Heat N/A J/(mol·K)

Phase Transition (Melting & Boiling Points)

Californium melts at 1173 K and boils at 1743 K.

Atomic Properties

Electron Config [Rn] 5f10 7s2

Electronegativity 1.3

Electron Affinity -97.31 kJ/mol

Ionization Energy 608 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

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.