Unit 4 Lesson 2 Periodic Trends Specific patterns

Unit 4 – Lesson 2

Periodic Trends Specific patterns that are present in the periodic table (mostly group A elements) related to certain properties

1. Atomic radius/diameter/volume (video) Use to label chart in your notes! • It is all about the SIZE of the atom NOT the mass • Atoms get larger going down a group because each period down adds one energy level (n). • Atoms get smaller going across a period because more protons pull the electrons closer to the nucleus. n= 1 2 3 4 5 6

• Which is the largest atom? F Br At • Which is the smallest atom? K Cu Kr • Order the atoms from largest to smallest. 3 Br 1 Ca 2 Ge • Order the atoms from largest to smallest. 1 Ba 3 C 2 K

Noble Gases not included 2. Electronegativity (video) • Ability to attract electrons in a chemical bond • Most electronegative → F Least electronegative → Fr • Noble gases have very little if any electronegativity b/c they have full valence shells. • The more electrons an element has in its valence shell the higher the electronegativity. RESULT → EN increases across periods left to right • As you move down groups, valence electrons get further away from the positive nucleus. RESULT → EN decreases down a group

Electronegativity Values DECREASING INCREASING

• Which is atom is the most electronegative? F Br At • Which is the least electronegative? K Cu As • Order the atoms from most to least electronegative. 1 Br 3 Ca 2 Ge • Order the atoms from most to least electronegative. 1 N 3 Bi 2 As

• Energy needed to pull off one electron (make an ion) Decreasing 3. Ionization Energy (video) • The higher the IE, the harder it is to remove an electron • Small atoms have a large IE because the electrons are very close to the positive nucleus • Atoms with a large EN have a large IE because if it is easy for the atom to grab electrons it will be very difficult to remove the electrons it has.

• Which is atom has the highest IE? Cl Br At • Which atom has the lowest IE? K Cu Kr • Order the atoms from highest to lowest ionization energy. 1 Br 3 Ca 2 Ge • Order the atoms from highest to lowest ionization energy. 1 N 3 Bi 2 As

4. Metallic Character • The more likely an atom is to lose an electron the stronger the metallic character • The further the valence shell is from the nucleus the easier it is to lose an electron so metallic character increases • As electronegativity or ionization energy increases, metallic character decreases.