LG: I can describe trends in the periodic table and explain the reasons for these patterns

Difficult to measure because outer edge of atom is not strictly defined Difficult to measure because outer edge of atom is not strictly defined Determined by measuring the distance between two nucleii and dividing by two Determined by measuring the distance between two nucleii and dividing by two Trends Trends Increases from right  left Increases from right  left Increases from top  bottom Increases from top  bottom

Every electron experiences a force of attraction toward the nucleus, called the effective nuclear charge. Every electron experiences a force of attraction toward the nucleus, called the effective nuclear charge. As you move down a group, we add energy levels that are progressively further from the nucleus As you move down a group, we add energy levels that are progressively further from the nucleus Lower energy levels ‘shield’ outer electrons from the pull of the nucleus Lower energy levels ‘shield’ outer electrons from the pull of the nucleus

Elements gain or lose electrons to form ions Elements gain or lose electrons to form ions The ionic radius of an element is always different than the atomic radius. In general: The ionic radius of an element is always different than the atomic radius. In general: Metals lose electrons to form smaller cations Metals lose electrons to form smaller cations Nonmetals gain electrons to form larger anions Nonmetals gain electrons to form larger anions

When an element loses electrons to obtain a full valence shell the resulting ion is smaller because: When an element loses electrons to obtain a full valence shell the resulting ion is smaller because: There are fewer electrons so each one experiences a greater effective nuclear charge There are fewer electrons so each one experiences a greater effective nuclear charge There is one less electron shell, so all electrons are closer to nucleus There is one less electron shell, so all electrons are closer to nucleus When an element gains e-, there is a lower effective nuclear charge When an element gains e-, there is a lower effective nuclear charge

I.E. is the energy required to remove a valence e- I.E. is the energy required to remove a valence e- E.N. measures the tendency of an atom to gain e- E.N. measures the tendency of an atom to gain e- I.E. and E.N. both increase from left  right and from bottom  top I.E. and E.N. both increase from left  right and from bottom  top

I.E. and E.N. decrease from top  bottom because valence e- are further from the nucleus I.E. and E.N. decrease from top  bottom because valence e- are further from the nucleus Electrons are easier to remove Electrons are easier to remove More difficult to attract e- from other atoms More difficult to attract e- from other atoms I.E. and E.N. increase from left  right because there is a larger effective nuclear charge I.E. and E.N. increase from left  right because there is a larger effective nuclear charge Stronger hold on e- Stronger hold on e- Stronger pull on e- from other atoms Stronger pull on e- from other atoms

Li, Na, K Li, Na, K What happens when alkali metals are put in water? What happens when alkali metals are put in water? Which one is the most reactive? Why? Which one is the most reactive? Why? Video (Brainiac) YrY Video (Brainiac) YrY

New Book: Pg. 41 #1 - 7, 10 New Book: Pg. 41 #1 - 7, 10