Chem Get Periodic Table Intro Packet stamped off if you did not do so last time Today: Periodic Trends If you will be absent on Friday, you will need to make arrangements to make up the lab. Periodic Table Quest Mon 3/19 (A) Tues 3/20 (B)

Groups you should know by name Group 1: Alkali Metals Note: Hydrogen is NOT considered an alkali metal Group 2: Alkaline Earth Metals Groups 3-12: Transition Metals Group 17: Halogens Group 18: Noble Gases

Review… 1. Why do all elements want to be like a noble gas? Noble gases have a full valence shell 2. In terms of electrons, what can elements do to try to become like a noble gas? Lose or gain electrons

Periodic Table of Elements Is organized By increasing atomic number Based on elements with similar properties

Rows Each Row is called a period

Columns Each column is called a group or family

As you go across a period (left to right): Does the number of energy levels change? Do you get closer or further from a noble gas element? NO CLOSER

As you go down a group (top to bottom): Does the number of energy levels change? Do you get closer or further from a noble gas element? YES (increases) Neither (no change)

Periodic Trends A periodic trend is a pattern for a specific characteristic of an element that is observed in the periodic table. These trends are general and have their exceptions.

Atomic Radius A measure of the size of an atom

Electronegativity A measure of an atom’s ability to gain or attract electrons Can be thought of as an atom’s desire or greediness for electrons (“greedy like the Grinch”)

Ionization Energy The amount of energy required to remove an electron from the outermost shell of an atom A measure of an atom’s ability to lose an electron and form a cation

Practice: Looking up Values in the Reference Table 1. Look up the atomic radius for Mg and Ca. Which one has a greater atomic radius? 1) Mg 2) Ca 140 174

Practice: Looking up Values in the Reference Table 2. Look up the electronegativity for Mg and Ca. Which one has a greater electronegativity? 1) Mg 2) Ca 1.3 1.0 It’s easier for Mg to gain electrons than Ca

Practice: Looking up Values in the Reference Table 3. Look up the ionization energy for Mg and Ca. Which one has a greater ionization energy? 1) Mg 2) Ca 738 590 It’s easier for Ca to lose electrons than Mg (requires less energy to remove it)

Periodic Trends War Get into groups of 4. Distribute the cards so that everyone has ONE card that is numbered 1-6 For each round, you will be comparing your element cards and a specific value from the reference table. As a group, order the cards from smallest value to largest value. Then, determine who wins the round based on who has the greatest value for the trend you are looking at for this turn. Fill in each row of the following table as you complete each round

#5 MC Round 6 part b: Therefore: Going across a period, the radius decreases Therefore: The element with the largest radius will be on the left (beginning) of the period Na has the largest radius