Download Atomic Structure and Periodic Table Quick Notes

Atomic Structure and Periodic Table Quick Notes
Atom: the smallest unit of an element that contains the properties of that element
Ex: if you have 1 gold atom, you can’t break that apart anymore and still have gold
 Nucleus: the center of an atom. Contains both Protons and Neutrons
 Protons are POSITIVE
Neutrons are NEUTRAL
Electrons are NEGATIVE- found in the electron cloud.
Atomic Structure and Symbols:
*Atomic Number: shows how many Protons are in the atom
*Atomic Mass: shows how many Protons + Neutrons are in the atom
*To find the number of Neutrons, simply subtract the Atomic Number from the Atomic
Mass
*Generally speaking, an atom will have the same number of Protons and Electrons,
(making it Neutrally Charged)
Two types of Atoms:
Ions- these are atoms that have LOST or GAINED an ELECTRON during a chemical reaction
 If an atom loses an electron, it becomes a Positive Ion
 If an atom gains an electron, it becomes a Negative Ion
Ex: when Na reacts with Cl to form NaCl, the Na atom loses an electron, making it a Positive Ion: Na+ The Cl, which gains the
electron, now has more negative particles than positive, becoming a Negative Ion: ClIons form when metals react with non-metals to form compounds. These types of chemical bonds are known as Ionic Bonds.
See other side for Isotopes and more information
Isotopes: these are elements that have abnormal numbers of Neutrons. They tend to be radioactive, and will undergo a radioactive
decay (remember: Alpha, Beta, Gamma)
- “normal” Carbon has an Atomic Mass of 12; this means it has a total of 12 Protons +
Carbon Isotope
Normal Carbon
Neutrons
A common isotope of Carbon, called Carbon 14 has an Atomic Mass of 14. It has 14
Protons + Neutrons, or 2 more Neutrons than “normal”; it is an ISOTOPE of Carbon.
Isotopes can have greater or fewer numbers
of neutrons.
6
6
NOTE: some texts and charts have the Atomic Number at the top of the symbol;
others have the Atomic Mass there! Do not rely solely on where the number is!
14-6 = 8
12-6 = 6
Understand what it is telling you- the Atomic Number is smaller than the Atomic
Mass, except for Hydrogen, which is the same. Hydrogen only has a proton and an electron.
Periodic Table and its Arrangement
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Periods are rows across; each element in the period gets more complex as you go right.
Groups/Families are in vertical columns. They are chemically similar.
Metals make up ¾ of the Periodic Table and are on the left t side of the chart
Non-metals are on the right.
Metalloids are in between the metals and non-metals.
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The numbers on the tops of the Families can help determine how many Valence Electrons in the atom