MS. SAMAYOA BIRMINGHAM COMMUNITY CHARTER HIGH SCHOOL CHEMISTRY PERIODIC TRENDS MS. SAMAYOA BIRMINGHAM COMMUNITY CHARTER HIGH SCHOOL CHEMISTRY

Learning Objective: Students will be able to explain periodic trends by studying the atomic radius, ionization energy, and electronegativity from a table Academic Vocabulary: Atomic radius, ionization energy, and electronegativity

ATOMIC RADIUS Atomic radius is the radius of an atom The distance from the atomic nucleus to the outermost stable electron orbital in an atom

Atomic radius What happens to the atomic radius when we go across a period? Decreases What happens to the atomic radius when we go down a group? Increases BUT WHY?

Let’s do some research HAVE TO KNOW: Protons have a positive charge (+) Electrons have a negative charge (-) Positive and negative are ATTRACTED TO EACH OTHER

ACROSS A PERIOD: FILL OUT THE FOLLOWING CHART USING THE PERIODIC TABLE Na Mg Al Si P S Cl Ar # of shells # of protons Atomic Radius (picometers) 166 141 121 111 107 105 102 106 Ionization Energy (kJ/mole) 496 738 578 787 1012 1000 1251 1521 Electronegativity (4 point scale) 0.9 1.2 1.5 1.8 2.1 2.5 3.0 ---

Down a group: fill out the chart using the periodic table # of shells # of protons Atomic Radius (picometers) Ionization Energy (kJ/mole) Electronegativity (4 point scale) H 31 1312 2.1 Li 128 520 1.0 Na 166 496 0.9 K 203 410 0.8 Rb 220 403 Cs 244 376 0.7

ATOMIC RADIUS ACROSS A PERIOD Na Mg Al Si P S Cl Ar # of shells 3 # of protons 11 12 13 14 15 16 17 18 Atomic Radius (picometers) 166 141 121 111 107 105 102 106 Ionization Energy (kJ/mole) 496 738 578 787 1012 1000 1251 1521 Electronegativity (4 point scale) 0.9 1.2 1.5 1.8 2.1 2.5 3.0 --- Noble gases have only van der waals radii because it cannot have covalent bonds with other elements Other elements can have covalent bonds with other elements As the number of protons increase, the atomic radius decreases.

THINK ABOUT IT… Why is it when the number of protons increase, the atomic radius decreases?

ATOMIC RADIUS DOWN A GROUP # of shells # of protons Atomic Radius (picometers) Ionization Energy (kJ/mole) Electronegativity (4 point scale) H 1 31 1312 2.1 Li 2 3 128 520 1.0 Na 11 166 496 0.9 K 4 19 203 410 0.8 Rb 5 37 220 403 Cs 6 55 244 376 0.7 As the number of shells increases, the atomic radius increases

THINK ABOUT IT… Why is it that when the number of shells increase, the atomic radius increases?

Ionization energy Ionization energy is the amount of energy required to remove an electron

Let’s do some research HAVE TO KNOW: Protons have a positive charge (+) Electrons have a negative charge (-) Positive and negative are ATTRACTED TO EACH OTHER

Ionization energy: across a period Na Mg Al Si P S Cl Ar # of shells 3 # of protons 11 12 13 14 15 16 17 18 Atomic Radius (picometers) 166 141 121 111 107 105 102 106 Ionization Energy (kJ/mole) 496 738 578 787 1012 1000 1251 1521 Electronegativity (4 point scale) 0.9 1.2 1.5 1.8 2.1 2.5 3.0 --- As the number of protons increase, the ionization energy increases

Why is it that when the number of protons increases, the ionization energy increases across a period?

Ionization energy: down a group # of shells # of protons Atomic Radius (picometers) Ionization Energy (kJ/mole) Electronegativity (4 point scale) H 1 31 1312 2.1 Li 2 3 128 520 1.0 Na 11 166 496 0.9 K 4 19 203 410 0.8 Rb 5 37 220 403 Cs 6 55 244 376 0.7 As the number of shells increase, the ionization energy decreases

Why is it that when the number of shells increases, the ionization energy decreases?

ELECTRONEGATIVITY Electronegativity is the power of an atom in a molecule to attract electrons to itself

ACROSS A PERIOD: ELECTRONEGATIVITY Na Mg Al Si P S Cl Ar # of shells 3 # of protons 11 12 13 14 15 16 17 18 Atomic Radius (picometers) 166 141 121 111 107 105 102 106 Ionization Energy (kJ/mole) 496 738 578 787 1012 1000 1251 1521 Electronegativity (4 point scale) 0.9 1.2 1.5 1.8 2.1 2.5 3.0 --- As the number of protons increases, the electronegativity increases

Why is it when the number of protons increases, the electronegativity increases?

DOWN A GROUP: ELECTRONEGATIVITY # of shells # of protons Atomic Radius (picometers) Ionization Energy (kJ/mole) Electronegativity (4 point scale) H 1 31 1312 2.1 Li 2 3 128 520 1.0 Na 11 166 496 0.9 K 4 19 203 410 0.8 Rb 5 37 220 403 Cs 6 55 244 376 0.7 As the number of shells increases, the electronegativity decreases

Why is it that when number of shells increases, the electronegativity decreases?