An atom is defined as the smallest part of a chemical element that retains the chemical properties of the element. Atoms are comprised of three subatomic particles called protons, neutrons and electrons. The positively charged protons and neutrons (which have no charge) make up the atom’s nucleus, or center, while the negatively charged electrons orbit around the nucleus. To accurately diagram an atom you must know how many protons, neutrons and electrons the atom contains, in addition to the atom’s “Electron Shell Configuration.”
Refer to the Periodic Table of Elements to learn the atomic number and atomic weight of the element for which you want to create a diagram. The Periodic Table is a grid-like chart displaying all known elements. Each individual grid square on the Periodic Table lists the atomic number, atomic symbol and atomic weight of each element; the elements are arranged in ascending order according to atomic number. To find the atomic number for the element you want on the Periodic Table, locate the grid square on the table assigned to that element by finding the element’s name or atomic symbol (the atomic symbol is the abbreviation of the element's name). The element’s atomic number is written in a small font at the top of each grid square; the atomic weight is written in small font at the bottom of the square.
Determine how many protons and electrons are in the selected element. An element’s atomic number represents the number of protons that element comprises. Since atoms have no overall electric charge, each atom has an equal number of protons and electrons. For example, a nitrogen (N) has an atomic number of 7, so a nitrogen atom is made up of seven protons and seven electrons.
Calculate how many neutrons the selected element is comprised of. The formula for finding out how many neutrons an atom has is:
Mass Number - Number of Protons = Number of Neutrons.
To find the Mass Number of an element, round its atomic weight to the nearest whole number. The nitrogen atom, for example, has an atomic weight of 14.0067. Rounded to the nearest whole number, nitrogen'sMass Number is 14. Subtract the number of protons to get 14 – 7 = 7; nitrogen has seven neutrons.
Draw a circle for each proton and each neutron contained in the selected element. Make sure these circles are clustered together. Place a positive sign inside each proton circle, or color each circle representing a proton the same color. Leave the inside of each neutron circle blank, or color all the neutron representative circles the same color. This cluster of circles represents the atom’s nucleus.
Find out the selected element’s “Electron Shell Configuration.” Nitrogen, for example, has an Electron Shell Configuration of: 1s^2 2s^2 2p^3; this means it has two shells with 2 electrons in the first shell and 5 electrons in the second shell because the “1” has a superscript number of 2; and the "2’s have superscript numbers of 2 and 3, which together make 5.
Draw one ring around the atom’s nucleus for each shell the atom has. Draw small circles on each ring to represent the number of electrons on that shell. The first shell is the ring closest to the nucleus.
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