Compare the Elements
Elements
are chemically the simplest substances and hence cannot be broken down using
chemical methods. Elements can only be changed into other elements using
nuclear methods.
Although an element's atoms must all have
the same number of protons, they can have different numbers of neutrons and
hence different masses.
When atoms of the same element have different numbers of neutrons, they are
called isotopes.
An element is a substance consisting
of atoms which all have the same number of protons - i.e. the same atomic
number.
With only one proton, hydrogen is the simplest, lightest element, followed by
helium, which has two protons.
The Most Abundant Elements
At 75 percent, hydrogen is also the most abundant
element in the universe, followed again by helium at 23 percent, then oxygen at
1 percent. Each oxygen atom has eight
protons. All of the other elements make up the remaining 1 percent.
In the earth's crust, oxygen (47 %) is the most
abundant element, followed by silicon (28 %)
and aluminum (8
%).
Element Names and Numbers
All of the elements have been named. Some of these
names are familiar to us, such as nitrogen and sodium, and some are less
familiar, such as dysprosium and roentgenium.
We can also name elements using their atomic
numbers. For example, element 1 is hydrogen, element 2 is helium, element 3 is
lithium, element 8 is oxygen, etc.
How Many Elements Are There?
There are currently 115 accepted elements and three
elements whose existence has been claimed, but not yet accepted (elements 113,
115 and 118).
We use the periodic table to display all of the
elements in an organized way.
Elements Ancient and Modern
Some elements have been known for thousands of
years, and we do not know who discovered them. These are: antimony, arsenic,
carbon, copper, iron, gold, lead, mercury, silver, sulfur, and tin.
All other elements have been discovered since 1669;
it was in this year that Hennig Brand became the first named person to discover
a new element - phosphorus.
Combining Elements
An element can combine with one or more other
elements to form compounds,
of which there are millions. For example, one of the best known compounds is
water, written chemically as H20, which means that water is made of
two atoms of hydrogen combined with one of oxygen.
How much nitrogen in our earth??thanks
BalasHapusAir consists of 3 main elements, namely dry air, water vapor, and aerosol. Dry air content is 78% Nitrogen, 20% Oxygen, 0.93% Argon, 0.03% Carbon Dioxide, 0.003% Other gases (Neon, Helium, Methane, Krypton, Hydrogen, Xenon, Ozone, Radon)
HapusYou explain about have different numbers of neutrons and hence different masses? can you explain, why? does any have same number of them?
BalasHapusIsotopes are a form of an element whose nuclei have the same atomic number, but the number of protons in the nucleus with different atomic masses because they have different numbers of neutrons.
HapusThe word isotope, meaning in the same place, comes from the fact that all the isotopes of an element are located in the same place in the periodic table.
Together, the isotopes of the elements form a set of nuclides
Please explain and provide proof why hydrogen ranks most in the universe. And give an example?
BalasHapusHydrogen is the most abundant element with a percentage of about 75% of the total mass of the elements of the universe. Hydrogen compounds are relatively rare and rarely found naturally on earth, and are usually produced industrially from various hydrocarbon compounds such as methane. Hydrogen can also be produced from water through an electrolysis process, but the process is commercially more expensive than the production of hydrogen from natural gas. This element is found in great abundance in stars and giant gas planets. The molecular clouds of H2 are associated with star formation.
Hapus