Thematic studiesElements, Compounds

and Mixtures

Done by: Wong Wei Cong (32) 1A1

CONTENTS Elements, compounds and mixtures Some terminology What is the most abundant element in the

universe Anatomy of a hydrogen atom Hydrogen in our solar system History of hydrogen Uses & problems of hydrogen Hydrogen bonding Hydrogen bomb The hydrogen age? Bibliography

Elements, Compoundsand Mixtures

IntroductionThe periodic table is a table displaying all the known elements. It is invented in 1869 by Russian chemist Dmitri Mendeleev, who wanted the table to illustrate recurring ("periodic") trends in the properties of the elements.

•An atom is the smallest division of an element which cannot be divided further, as its name suggests.

•It consists of a heavy nucleus, containing positively-charged protons and electrically-neutral neutrons, surrounded by a cloud of light, negatively-charged electrons; which stay together with the nucleus by electromagnetic force.

•Protons and neutrons behave like small particles, kind of like tiny balls; while electrons have some of the properties of a wave. 

•An atom with an equal number of protons and electrons is electrically neutral; one that has a positive or negative charge is an ion.

•Two or more atoms with different numbers of neutrons are called isotopes. 

Some terminology…

Isotope of hydrogen: Deuterium

Positively-charged hydrogen atom

Hydrogen atom

Negatively-charged hydrogen atom

WHAT IS THE MOST ABUNDANT ELEMENT IN THE UNIVERSE?

Hydrogen Hydrogen is the lightest and most abundant element in the

Universe, making up roughly three-quarters of the Universe's mass and over 90% by number of atoms.

The symbol for hydrogen is H and its atomic number is 1. Its name is derived from the Greek ‘Hydro Genes’, which means “water-former”, because hydrogen produces water when burned.

Electrolysis of water. Electricity is used to split water into hydrogen and oxygen.

ANATOMY OF A HYDROGEN ATOM•A hydrogen atom is made up of one proton and one electron. Hydrogen is the only element without neutrons.

•Hydrogen has three naturally occurring isotopes: 1H (protium), 2H (deuterium) and 3H (tritium).

Plasma hydrogen

Hydrogen in our solar system•Our Sun is mainly composed of plasma hydrogen. Hydrogen is important in the forming and powering of stars.

•Jupiter and the other gas planets are primarily made up of hydrogen. At a certain point deep inside the planet, the immense pressure converts the solid non-metallic hydrogen into solid metallic hydrogen.

•Hydrogen is relatively rare in the Earth’s atmosphere. It is light, so it is able to escape Earth’s gravity more easily then heavier gases.

•However, hydrogen is the third most abundant element on the Earth’s surface. It is present in water (H20) and most organic compounds. It is also produced by some bacteria and algae.

HISTORY OF HYDROGEN•Hydrogen gas (H2) was first artificially produced in the early 16th century.

•Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance and that it produces water when burned.

•At standard temperature and pressure, hydrogen is a colourless, odourless, tasteless and highly flammable gas.Why blimps are now filled with helium instead of hydrogen

Uses & problems of hydrogen•Hydrogen is used in processing fossil fuels, and used to make ammonia for fertilisers and methanol.

•Liquid hydrogen is used as rocket fuel.

•Deuterium and tritium are used in nuclear fusion (multiple atomic nuclei combining together to form a single heavier nucleus) to generate electricity.

•In mitigating the effects of global warming, when hydrogen is produced from fossil fuels, long-term storage of CO2 could be conducted with hydrogen as a carrier of energy.

Uses & problems of hydrogen (II)•The hydrogen economy could be an alternative to our current oil and coal based economy.

•When hydrogen burns with oxygen, the only by-product from the reaction is water.

•Hydrogen fuel cells are increasingly being seen as pollution-free energy sources.

•Hydrogen can cause many metals to become brittle, posing a problem to the design of pipelines and storage tanks.

•A hydrogen bond refers to a hydrogen atom attaching to another atom, like nitrogen, oxygen or fluorine.

•Hydrogen shares electrons with another atom to create the bond.

•The bond is present in water and DNA.

•Hydrogen bonding between molecules is responsible for the high boiling point of water (100 °C).

•Hydrogen bonding within a molecule plays an important role in the structure of proteins and nucleic acids like DNA, and also the structure of man-made and natural polymers (plastics).

Hydrogen bonding

Hydrogen bonding (II)

Hydrogen bonds in DNA Hydrogen bonds in polymers

Hydrogen bonds in cellulose

HYDROGEN BOMB•A hydrogen bomb is a weapon obtaining its energy from the nuclear fusion of hydrogen isotopes; unlike an atomic bomb, where the nuclei of uranium or plutonium atoms are split into smaller parts, producing energy.

•At the centre of a hydrogen bomb is an atomic bomb, with a layer of lithium deuteride (a compound of lithium and deuterium) surrounding it; while around it is a thick outer layer.

• Neutrons from the atomic explosion cause the lithium to fission into helium, tritium, and energy.

Hydrogen bomb (II)

ConclusionThe uses of hydrogen does not end here. Energy is the universal currency on Earth. Conventional fossil fuels have a notorious reputation of polluting the Earth. Furthermore, they are depleting fast. That is where comes “The Hydrogen Age”. As quoted from “The Hydrogen Age: Empowering a Clean-Energy Future” by Geoffrey Holland, James J. Provenzano, “The word is entering The Hydrogen Age. That is a very good thing. It will mean cleaner skies. It will address global warming in the most effective way possible. It will eliminate our dependence on foreign oil and end the political conflict driven by our oil addiction. These are all the things we can celebrate. The really great news is this exciting energy transition will not be a drag to the economy. On the contrary, it will stimulate unprecedented economic opportunity. Millions of good jobs will be created over the years it will take to fully implement this bold, clean energy vision. We need to do it now, and we can do it now.”

The Hydrogen age?

THE HYDROGEN AGE?

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