noble gas envy ions

ChemCatalyst One atom of Lithium and one atom of Fluorine form a very strong bond. This is because the lithium atom gives up its valence electron to the fluorine atom. 1. What benefit occurs to either atom as a result of the transfer of the electron? Unit 1 • Investigation V 2

Why would atoms want to gain or lose electrons?

Stability This is because they have the maximum number of valence electrons allowed

What is the maximum number of valence electrons any atom can have?

Except for hydrogen and helium, It is 8

What atoms have a full valence shell?

Noble gases

Noble Gas Configuration and reactivity All atoms want their valence electron shell filled This is the most stable electron configuration Once valence shell is filled, atom stops reacting to or bonding with other atoms. Since noble gases start out with a filled shell, they do not react with any other substance

Why some atoms gain electrons and some lose electrons Remember, the goal of all atoms is to have a full valence shell Except for helium, a full shell has ____ electrons Atoms will gain or lose electrons to fill or empty the shell

Actions of atoms Atoms with 5-7 electrons want to add electrons to fill the outer shell Atoms with 1-3 electrons want to lose all electrons in that outermost shell Atoms with 4 electrons and Hydrogen atoms can either gain or lose electrons

Ion An atom that gains or loses control of electrons is called an ion All ions are no longer neutral, because they have a different number of electrons compared to protons

Lab Task, part 1 To create several sets of Ion cards for the class Working in teams of 4 to complete one set (each person completes 7 cards) Each card indicates the following information on one atom: Name Symbol Atomic number, mass of most common isotope # Valence electrons (electron config. for honors) # Core electrons A Bohr diagram that indicates Number of protons and neutrons and shows the electrons as circles on the rings

Division of cards Team member 1: H, Ca, B, Si, As, F, Ne Team Member 2: Li, Mg, Al, Ge, O, Cl, Ar Team Member 3: Na, Be, Ga, N, S, Br, He Team Member 4: K, He, C, P, Se, Kr, Cl

Example Mass of most common isotope: Round the Atomic mass on the periodic table Core electrons: number of electrons not on the outer ring Beryllium Be At#: 4 Mass: 9 Valence: 2 [He] 2s2 Core: 2

On Bottom of card Indicate whether atoms wants to gain or lose electrons to obtain Noble Gas Configuration Indicate how many electrons will be gained or lost to achieve NGC On bottom of card write “Ion type:” and leave blank

Example, revisited again Cations are atoms that want to lose electrons Name : symbol,# electrons lost, + sign Anions are atoms that want to gain electrons Name: symbol, # electrons gained, - sign Beryllium Be At#: 4 Mass: 9 Valence: 2 [He] 2s2 Core: 2 Wants to lose 2 e- Ion type: Cation Be2+

Complete information at the bottom on all cards

Cation An atom that has lost electrons More protons than electrons results in a positive charge Na+, Ca 2+, B 3+

Anion An atom that has gained electrons Less protons than electrons results in a negative charge F-, O2-, P3-

Example, revisited for 3rd time Atoms with 5-7 electrons want to add electrons to fill the outer shell Atoms with 1-3 electrons want to lose all electrons in that outermost shell Atoms with 4 electrons and Hydrogen atoms can either gain or lose electrons Atoms with 8 electrons or Helium do not gain or lose electrons Beryllium Be At#: 4 Mass: 9 Valence: 2 [He] 2s2 Core: 2 Wants to lose 2 e- Ion type:

Fill out Ion type, name for all cards

Bi Ba Lewis dot structure Drawn when only valence electrons are important The center of the structure is the symbol of the element Dots (which represent valence electrons), are placed on any side of the symbol (including top and bottom) No more than 2 dots on any side Bi Ba

Turn you cards over Draw the Lewis Dot diagram for each card Make sure symbol and dots fill most of page Write your name on the bottom of each card

Form Groups Teams of 4 Each member will have a different number 1-4 Arrange the cards as the elements appear in the periodic table

Questions to be answered by the group Describe the position occupied all the potential Cations, Anions be located in the cards? In the periodic table? 1a) Turn over the cards so that their Lewis dot diagrams show. Add up the number of dots showing on lithium and fluorine combined. These atoms formed a bond. What must be true for any pair of atoms that forms a bond? 2. Name 10 pairs of elements would like to bond together. 3. Name 5 pairs of elements that would never bond together (may not include noble gases) 4. What element would like to combine with 3 hydrogen atoms? List all possibilities

Lab group questions, continued 5) Determine which of the following could be real compounds: NaF, SrXe, MgO, SbRb3 6) To be a real compound what must the sum of all the components valence electrons be? 7) In order to be a compound, there must be at least one Cation and one Anion. For the compounds in question 5 identify which components are Anions or Cations and write their name

The Big Question What ion charges are formed when atoms attain a noble gas electron configuration? Unit 1 • Investigation V 28

You will be able to: Predict what would have to happen for potassium to obtain a noble gas configuration. Unit 1 • Investigation V 29

Activity Purpose: You will explore the ions that are formed when atoms give up and receive electrons from other atoms. Unit 1 • Investigation V 30

Notes Unit 1 • Investigation V 31

Making Sense Why do you think the noble gas configuration is especially stable? Unit 1 • Investigation V 32

Notes A valuable piece of information helps us predict which ions might be encountered in chemistry: Atoms tend to lose or gain electrons to attain the electron configuration of the noble gas nearest to it on the periodic table. (cont.) Unit 1 • Investigation V 33

Atoms with a positive charge are called cations. Ion Names Atoms with a positive charge are called cations. Atoms with a negative charge are called anions. Unit 1 • Investigation V 34

Check-In Write the electron configuration or draw the Lewis Dot Diagram for potassium, K. What would have to happen for potassium to have a noble gas configuration? Explain. What would have to happen for an atom of K to become stable? Is it a cation or anion? Unit 1 • Investigation V 35

Wrap-Up Noble gases are stable with filled outermost s and p subshells. Atoms can gain or lose electrons to end up with a noble gas configuration. When atoms lose electrons, they have a positive charge and are called cations. When atoms gain electrons, they have a negative charge and are called anions. Unit 1 • Investigation V 36

Where do the electrons go if their released Where do electrons come from if they are gained?