SWBAT Identify trends on the periodic table Bellringer: On HALF SHEET to be turned in I am shiny, able to conduct electricity and easily molded. What am I? I am HIGHLY reactive and am often used as disinfectants. What am I? I am very unreactive and often am used to make colorful lights. What am I? I am in Group 17, Period 2. What am I?

Trends in the periodic table: Atomic Radius Ionization Energy Electronegativity

Atomic Radius Atomic Radius = half the distance between 2 bonded atoms. Why can’t we just measure from the nucleus to the outer electron shell?

Atomic Radius H Li Na K Rb As we increase the atomic number (or go down a group). . . each atom has another energy level, so the atoms get bigger. Li Na K Rb

Atomic Radius Na Mg Al Si P S Cl Ar Going from left to right across a period, the size gets smaller. Electrons are in the same energy level. But, there is more nuclear charge. Outermost electrons are pulled closer. Na Mg Al Si P S Cl Ar

Atomic Radius

increases

CHAT CHUMS! 1. Which has a larger radius for each: Explain why. Cl or Al Li or Ne Explain why. Why do we measure the radius as ½ the space between 2 nuclei? Why can’t we do it the same as in math?

Ions Some compounds are composed of particles called “ions” An ion is an atom (or group of atoms) that has a positive or negative charge Atoms are neutral because the number of protons equals electrons Positive and negative ions are formed when electrons are transferred (lost or gained) between atoms

Ionization Energy Amount of energy required to remove an electron

Ionization Energy Group Trend – As you go down a column, ionization energy decreases. -As you go down, atomic size is increasing (less attraction), so easier to remove an e-. Periodic Trend – As you go across a period (L to R), ionization energy increases. -As you go L to R, atomic size is decreasing (more attraction), so more difficult to remove an e- (also, metals want to lose e-, but nonmetals do not).

Ionization Energy (IE) Trends (IE) Increases Up the Periodic Chart. (IE) Increases from Left to Right

CHAT CHUMS 1. Which has a higher ionization energy? Ca or Cl P or O 2. In your own words, explain why ionization energy and atomic radius follow an opposite trend pattern on the periodic table.

Electronegativity Electronegativity- tendency of an atom to attract e-. -The ability of an atom to pull electrons in a chemical bond. -Due to pull from protons and how close electrons are to nucleus. More electronegative = stronger pull on electrons Same pattern as ionization energy (IE)

Electronegativity Trend Group Trend – As you go down a column, electronegativity decreases.` As you go down, atomic size is increasing, so less attraction to its own e- and other atom’s e-. Periodic Trend – As you go across a period (L to R), electronegativity increases. As you go L to R, atomic size is decreasing, so there is more attraction to its own e- and other atom’s e-.

CHAT CHUMS 1. Which is more electronegative? Ca or Cl P or O 2. In your own words, explain why ionization energy and electronegativity follow the same trend pattern on the periodic table.

Practice! Practice: Periodic Trends EPAS Passage 3

Flash cards! Metalloids! (Stairstep elements) Trends (Atomic Radius, Ionization Energy, Electronegativity) Element types & characteristics (metals, non metals, metalloids, alkali, alkaline earth, transition, halogen, noble gas)