Parts of the Atom
Investigation Questions
Consider an atom of 26 electrons:
1. Which is its atomic number?
2. How many protons and neutrons does it have?
3. What is its name and symbol?
4. How can we predict the path of an electron in this atom?
One of the biggest mysteries of Science, is the composition of matter, it is, the atom. Chemists and Physicists are still working to find an accurate answer that seems to be escaping from our eyes.
The atom is the smallest part of matter, it means that each element is made of atoms, elements combine to form molecules and compounds. The atom has many sub-atomic particles, every one with a special characteristics, but the main ones we are going to study are the proton and the neutron in the nucleus, and the electrons spinning around in the electron cloud. The proton has an electric positive charge and the electron is negative. Both exist in the same amount. The neutron has a neutral charge and can vary in quantity respecting to the protons.
The atom in numbers
The atom can be described by the number of subatomic particles.
Atomic Number (Z): It shows the number of protons within an atom. It is used to identify a determined element. Remember that the atom has the same number of protons and electrons, so Z can also indicate the number of electrons.
Symbol: It's a given code of an uppercase letter related to the name or the element that identifies it on a given formula. It can also be the first two letters, with the first one in uppercase, andthe second lowercase to avoid cofussion.
Name
Mass number: It indicates the average number of protons and neutrons within an atom
7
N
Nitrogen
14,01
Finding the mass...
The atomic mass of an atom is given mostly by he average mass of protons and neutrons rather than electrons.
The AMU scale: It's so small, that it is given as a 6 p and 6 e carbon atom with a mass of 12 AMU, so an AMU unit would be 1/12 of the mass of this atom, so the average mass of a proton or a neutron is 1, and for an electron is 2000 times much smaller than a proton or a neutron.
Click on the table to see more information
An Isotope is a form of an atom of the same element with different number of neutrons. The atomic mass can be calculated by multiplying each isotope by its percent abundance, and then, by adding each result.
