Download Elements in our universe

Elements in our universe
By: Jonathan Choong 1A1 (10)
:D
Contents
 Definition of elements
 Atomic mass ,atomic number and isotopes
 Element names
 Atomic bomb?
 Use of elements/compounds
 Discovery of elements
 How elements are formed
 Abundance of elements
 Properties of elements
 Bibliography
Definition of an element
 Atomic nucleus – contains neutrons and protons also known
as nucleons.
 A chemical element is a pure chemical
substance consisting of one type of atom distinguished by
its atomic number, which is the number of protons in
its nucleus.
Atomic number, atomic mass and
isotopes
 The atomic number indicates the number of protons within
the nucleus of an atom
 Atomic mass is the mass of an atom measured in atomic mass
units, when the atom is at rest at its lowest energy level.
 Isotopes are elements of different forms. This is caused by the
varying number of neutrons in each atom. Isotopes may have
the same atomic number but different atomic mass.
Atomic bomb?
 Weapon getting its explosive force from the release of atomic
energy through the fission (splitting) of heavy nuclei.
 Nuclear energy is the energy stored in the nucleus of an atom
and released through fission, fusion, or radioactivity . In these
processes a small amount of mass is converted to energy.
Halogens
 Compounds that contain halogens are known as salts – group
17.
 For example, sodium chloride is made up of chlorine which
is a halogen.
How elements are formed
 Nucleosynthesis is the process of creating new atomic
nuclei from pre-existing nucleons (protons and neutrons).
 Stellar nucleosynthesis – As the star undergoes stellar
evolution , it generates elements
from carbon to iron by nuclear fusion processes.
 nuclear fusion is the process by which multiple atomic nuclei
join together to form a single heavier nucleus.
Abundance of elements
 Hydrogen is the most abundant element in the universe, followed
by oxygen.
Properties of elements
 Elements on the periodic table are classified into alkali metal,
alkaline earth, basic metal, halogen, noble gas, non-metal,
rare earth, semi-metal, transitional earth.
 Periodic table is organised according to similar properties,
groups also have similar properties and one can predict the
properties of an element by observing where it is place on
the periodic table.
bibliography
 http://en.wikipedia.org/wiki/Nucleosynthesis#Processes
 http://www.encyclopedia.com/topic/atomic_bomb.aspx
 http://www.newworldencyclopedia.org/entry/Isotope
 http://en.wikipedia.org/wiki/Nuclear_fusion
 http://www.newworldencyclopedia.org/entry/Atomic_mass
 http://www.chemicalelements.com/groups/halogens.html
 http://www.ask.com/wiki/Abundance_of_the_chemical_elem
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