Page 44 - Curriculum Visions Dynamic Book

Key facts about...
Hydrogen
Liquid hydrogen is one- tenth as dense as water
Can be explosive and inflammable
Its isotope tritium is radioactive
Its isotope deuterium is not radioactive. Deuterium oxide is known as “heavy water”
A colourless gas, chemical symbol H
Atomic number 1, atomic weight 1
Low density gas (less than one-twelfth as dense as air)
Has no taste Has no smell
Insoluble in water
Comprises about 99.88% of the Universe
SHELL DIAGRAMS
The shell diagrams on these pages are representations of an atom of each element. The total number
of electrons are shown in the relevant orbitals, or shells, around the central nucleus.
Electron shell
Electron
Nucleus containing protons and neutrons (called nucleons)
 Halogen lamps are filled with a mixture of xenon and a halogen vapour. They are essentially incandescent lights.
Helium
Has no smell Has no taste
A colourless gas, chemical symbol He
Atomic number 2, atomic weight about 4
Inert
Nontoxic