Periodic Table

The periodic table is a chart containing information about the atoms that make up all matter. It is called the periodic table of elements because elements are made of the same kind of atom.

Periodic Table In the periodic table we can learn element’s names, their atomic number, number of protons, neutrons, and electrons, number of valence electrons and atomic mass.

Element An element is a substance made up of only one type of atom. ATOMIC NUMBER ELEMENT SYMBOL ELEMENT NAME ATOMIC MASS

Atomic Number The atomic number of an atom is equal to the number of protons in its nucleus. How many protons to the following elements have? a) magnesium b)lead c)aluminum

Number of Electrons All neutral atoms have the same number electrons as protons. The atomic number tells us the number of protons, and it also tells us the total number of electrons. The number of electrons surrounding the nucleus of an atom is equal to the number of protons in its nucleus. How many electrons do the following elements have? a)potassium b)sulfur

Atomic Mass The atomic mass tells us how much an atom weighs. Atomic mass is equal to the number of protons plus the number of neutrons. Atomic mass is measured in “atomic mass units” (amu)

Demo

Atomic Mass -Xenon -atomic mass of amu -Protons + Neutrons = amu

Atomic Mass Xenon has an atomic mass of amu To find the number of neutrons 1) We round the atomic mass: 131 amu 2) We subtract the atomic number from the atomic mass: 131 – 54 = 77 -(atomic mass - # protons = # neutrons) -(Big # – small # = # of neutrons)

Atomic Mass Using your Periodic Table of Elements find the atomic mass of the following: 1)Nitrogen 2)Barium 3)Mercury 4)Argon

Number of Neutrons To find the number of neutrons: 1)We round the atomic mass: 2)We subtract the atomic number from the atomic mass: (atomic mass - # protons = # neutrons) How many neutrons do the following atoms have? Show your work! a) berylliumb) sodium

Finding Number of Neutrons Example Xenon has an atomic mass of amu To find the number of neutrons 1) We round the atomic mass: 131 amu. 2) We subtract the atomic number from the atomic mass: 131 – 54 = 77 -(atomic mass – # protons = # neutrons) -(Big # – small # = # of neutrons)

Periods Periods are the horizontal rows in a periodic table. Periods tell us about how electrons sit around the nucleus, depending upon the element. Write the period number beside each row.

Groups/Families Groups or families are the vertical columns in a periodic table. All the elements in the same group have the same number of valence electrons. All the elements in the same group have similar chemical characteristics. Write the group number that has the letter A beside it for each group.

Valence Electrons Electrons have different orbits around the nucleus. Valence electrons are the electrons that are on the outermost orbit. We can tell how many valence electrons an element has based on which group it is in. Look at the groups with the letter ‘A’ in them!

Valence Electrons How many valence electrons do the following elements have? 1)Boron 2)Chlorine 3)Calcium 4)Cesium 5)Oxygen