Families of the PT

Warm-up How many valence electrons do atoms of oxygen and sulfur have? How do you know? Look at the element box for Carbon on your periodic table. What does the number represent? How is it calculated?

Warm-up Explain how a calendar is similar to a periodic table and how it is different. Why are halogens found in nature only in compounds?

Alkali Metals Group 1 (1 valence electron) EXTREMELY chemically reactive o Found in nature only in compounds because they are so reactive o Reactivity increases from top of group to bottom of group Soft, silvery metals if not combined with other elements Examples of compounds containing Alkali metals? Hydrogen is NOT an Alkali metal, it is a nonmetal!

Sodium in Water

Alkaline Earth Metals Group 2 (2 valence electrons) Harder than Group 1 metals Reactivity varies Mg: A mixture of metals that includes magnesium can be as strong as steel but much lighter (used in bicycle frames) Ca: Used in your body to keep bones and teeth strong; found in chalk, limestone, coral, casts (for broken bones), and toothpaste

Halogens Group 17 (7 valence electrons) EXTREMELY chemically reactive Nonmetals React easily with most metals Many practical uses of halogens, from killing bacteria (chlorine) to preventing tooth decay (fluorine)

Noble Gases Group 18 o Helium has only 2 valence electrons o All other elements in Group 8 have 8 valence electrons Extremely UNREACTIVE Colorless and odorless

Chapter 6 Electron Configurations & Ions

Warm-up As we move across the periodic table from left to right, what happens to the metallic nature of the elements? Which group of elements is the most unreactive? Draw electron dot diagrams for all of the elements in this group. What do they have in common?

Stable Electron Configuration Chemical properties (like reactivity) depend on an element’s electron configuration When the highest occupied energy level of an atom is filled with electrons, the atom is stable and NOT likely to react Elements that do not have complete sets of valence electrons tend to react

Predicting… Which group of elements has a complete set of valence electrons What would the Halogens need in order to become stable?

Octet Rule A chemical rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells All atoms are trying to achieve the electron configuration of noble gases Atoms will gain, lose, or share electrons in order to become stable

Atoms will GAIN, LOSE or SHARE electrons in order to become stable!

Ion Formation Ion (definition) o An atom that has a net negative or positive electrical charge When an atom gains or loses electrons, the number or protons (+ charge) is no longer equal to the number of electrons (- charge) o The charges will NOT be balanced, so the atom will NOT be neutral

Types of Ions AnionsCations An ion with a negative charge An ion with a positive charge

How do Ions Form? Atoms want to be like noble gases o This means they need to have only 8 electrons in their outer shell Atoms can get rid of electrons (making them MORE positive) Atoms can steal electrons (making them MORE negative) So do they give up electrons or steal them? o They do whatever is easier !!!

Example 1 Sodium (Na)Chlorine (Cl) Draw a dot diagram AND a Bohr diagram for Na Draw a dot diagram AND a Bohr Diagram for Cl

Example 2 Magnesium (Mg)Oxygen (O) Draw a dot diagram for Mg Draw a dot diagram for O

Warm-up What is the difference between a cation and an anion? Why are some elements chemically reactive while some are NOT chemically reactive? What is the name given to the group of elements that are chemically stable? Why are they stable?

Ion Charge The charge of an ion is used to predict chemical formulas o Chemical formulas are notations that show what elements a compound contains and the ratio of the atoms or ions of these elements in the compound To identify an ion, write the chemical symbol and then a superscript number that indicates the charge of the ion

Identifying Ions/ the Charge of Ions H

Group Practice Each person in your group should take 30 seconds to explain how to find the charge of an ion Ion Charge Races o An element will be shown on the board. The first team to legibly predict the charge of the ion (on a white, dry-erase board) wins the round. o Playing for blow-pops HOMEWORK o Ion Charge Practice Worksheet

Ca

Se

Kr

K

F

P

Li

Be

B

I

Mg

He

Br

Na

O

H

Al

N

S

Ne