Science Questions And Answers About the Chemical Element Hydrogen
Hydrogen is a chemical element with what chemical symbol?
A: H.
What is the atomic number for hydrogen?
A: 1.
What is the atomic weight of hydrogen?
A: 1.00794.
Hydrogen is the lightest element on the what?
A: Periodic table.
Its monatomic form (H) is the most "what" in the universe?
A: Abundant chemical substance.
Hydrogen constitutes roughly 75% of all what?
A: Baryonic mass.
Non-remnant stars are mainly composed of what?
A: Hydrogen in its plasma state.
The most common isotope of hydrogen, termed protium (name
rarely used, symbol 1H), has what?
A: A single proton and zero
neutrons.
When did the universal emergence of atomic hydrogen first
occur?
A: During the recombination epoch.
Hydrogen readily forms covalent compounds with most what?
A: Non-metallic elements.
Most of the hydrogen on Earth exists in what form?
A: Molecular forms such as in the form of water or organic compounds.
Hydrogen plays a particularly important role in what type
of reactions?
A: Acid–base.
When was hydrogen gas first artificially produced?
A: In the early 16th century, via the mixing of metals with acids.
In 1766–81, Henry Cavendish was the first to recognize that
hydrogen gas was a what?
A: Discrete substance, and that it produces water when burned.
What does hydrogen mean in Greek?
A: "water-former".
Industrial production is mainly from what?
A: The steam reforming of natural gas.
Most hydrogen is employed near its production site, with
the two largest uses being what?
A: Fossil fuel processing (e.g., hydrocracking) and ammonia production, mostly
for the fertilizer market.
Hydrogen is a concern in metallurgy as it can what?
A: Embrittle many metals.
The Space Shuttle Main Engine burnt hydrogen with oxygen,
producing what?
A: A nearly invisible flame at full thrust.
Hydrogen gas is highly what?
A: Flammable.
Hydrogen gas forms explosive mixtures with air if it is
what?
A: 4–74% concentrated.
Hydrogen gas forms explosive mixtures with chlorine if it
is what?
A: 5–95% concentrated.
The mixtures may be ignited by what?
A: Spark, heat or sunlight.
What is the hydrogen autoignition temperature?
A: In air, is 500 °C (932 °F)
Pure hydrogen-oxygen flames emit what type of light?
A: Ultraviolet.
Hydrogen flames in other conditions are what
color?
A: Blue, resembling blue natural gas flames.
The destruction of the what, was an infamous example of
hydrogen combustion?
A: Hindenburg airship.
H2 reacts with every what?
A: Oxidizing element.
Hydrogen can react spontaneously and violently at room
temperature with what?
A: Chlorine and fluorine.
What is the ground state energy level of the
electron in a
hydrogen atom?
A: −13.6 eV.
Protium, the most common isotope of hydrogen has how many
electrons and protons?
A: One proton and one electron.
Unique among all stable isotopes, it has no what?
A: Neutrons.
H is the most common what?
A: Hydrogen isotope with an abundance of more than 99.98%.
Because the nucleus of this isotope consists of only a
single proton, it is given formal name?
A: Protium.
The other stable hydrogen isotope, is known as what?
A: Deuterium.
Deuterium contains what in its nucleus?
A: One proton and one neutron.
Essentially all deuterium in the universe is thought to
have been produced when?
A: At the time of the Big Bang.
Deuterium is not radioactive, and does not represent a
what?
A: Significant toxicity hazard.
Water enriched in molecules that include deuterium instead
of normal hydrogen is called what?
A: Heavy water.
Heavy water is used as a what for nuclear reactors?
A: Neutron moderator and coolant.
Deuterium is also a potential fuel for what?
A: Commercial nuclear fusion.
