Presentation on theme: "How they are formed. Valence Electrons Valence Electrons of an atom are the electrons that are in the outermost s and p sub shells. (ONLY S AND P) To."— Presentation transcript:
How they are formed
Valence Electrons Valence Electrons of an atom are the electrons that are in the outermost s and p sub shells. (ONLY S AND P) To determine how many electrons are in your valence shell, look at where your element is on the periodic table.
Valence Electrons Ex. Sodium- Na- In the s-block. Only 1 electron in the outermost s sub shell. You can look at the electron configuration to help as well 1s 2 2s 2 2p 6 3s 1 - The 3s sub shell is the outermost shell. It only has 1 electron in it. There fore it only has 1 valence electron
Valence Electrons Lets look at something that lies in the p sub shell. Sulfur- S - 1s 2 2s 2 2p 6 3s 2 3p 4 - Remember valence electrons are in both the outermost s and p sub shells How many Valence electrons? Lets look at Bromine. How many valence electrons does it have?
Valence Electrons Hint- Column 1 will always have 1 valence electron Column 2 will always have 2 valence electrons Column 13 will always have 3 valence electrons Column 14 will always have 4 valence electrons Column 15 will always have 5 valence electrons Column 16 will always have 6 valence electrons Column 17 will always have 7 valence electrons Column 18 will always have 8 valence electrons
Valence Electrons How many Valence electrons do the following elements have? Calcium – Ca Cesium – Cs Iodine – I Krypton – Kr Carbon – C Polonium – Po
Lewis Dot diagrams Lewis Dot Diagrams, or Electron dot structures, are diagrams that show valence electrons as dots
Lewis Dot Diagrams Practice: How many Valence Electrons and LDD Calcium Ca- Cesium Cs – Krypton Kr – Polonium Po-
Octet Rule Notice how Krypton ( a Noble Gas) Has filled up its valence electrons. This is why Noble Gases do not form ions or bond with anything. They are perfectly content with being filled all the way. All the other elements are jealous and want to be like the Noble Gases, so they have to take on or lose electrons to take on this filled Valence Shell Octet Rule states- Atoms react by gaining or losing electrons so as to acquire the stable elecron structure of a noble gas, usually eight electrons.
Cations and Anions To become more like the noble gases, all the other elements will start to either gain or get rid of electrons to fill out a Valence Shell Whether an element gains electrons or loses them depends on where it is on the periodic table and what kind of material it is
Anions Anions are formed by non-metals (to the right of the metalloids) Anions will gain electrons to become negatively charged ions Because Noble Gases already have a full valence shell, you will not find them becoming ions of any sort
Anions Nitrogen- forms a -3 charge Oxygen – forms a -2 charge Sulfur – forms a -2 charge Fluorine – forms a -1 charge Chlorine – forms a -1 charge Bromine – Forms a -1 charge Iodine – Forms a -1 charge
Cations Cations are metals. The metals typically only have just the s sub shell filled in the valence shell. It is easier to lose electrons to become more like a Noble Gas then to gain them Cations will lose electrons and then therefore become positively charged.
Cations Column 1 will lose 1 Valence electron and form a +1 charge (Hydrogen can both lose and gain 1 electron depending on what situation it is in) Column 2 will lose 2 valence electrons and form a +2 charge
Practice What Charge does each Element Make? Sr Al P Cl Kr
Transition Metals (D-block) The transition metals make multiple positive ions. The way that you will be able decide what charge that transition metal is will be determined by either having the name written out or by looking at the chemical formula of the compound that it will make
When Given the Written Name When you are given the written name of a chemical formula with a transition metal in it, it will give you a roman numeral in parenthesis. The Roman numeral is the charge that the transition metal will take Remember that Transition metals are all going to form positive ions or cations. Ex. Iron (II) Chloride- Fe 2+ reacting with Cl 1-
When Given the Chemical Formula When you are given a chemical formula with a transition element in it, Determine the charge of the anion first ( Anions do not change their charge in Ionic compounds) Then give the charge to the Transition metal that will negate the negative charge Ex. FeCl3 – Chlorine has a charge of -1. There are three chlorines. That gives a total charge of -3. To make this a neutral atom, you must have a +3 charge to balance that out. Fe (iron) must have a +3 charge.
Practice Give me the charge of the transition element Lead (IV) Bromide Copper (I) Fluoride ZnO Ni 2 O 3
Poly Atomic Ions Poly atomic ions are those that are formed by more than one type of element. Can be 2 or more different elements (usually not more than 3) Example – Nitrate Ion is NO 3 - Notice that there are two different elements, Nitrogen and Oxygen
Common Polyatomics Hydroxide – OH 1- Hypochlorite – ClO 1- Nitrate – NO 3 1- Acetate - C 2 H 3 O 2 1- Bicarbonate – HCO 3 1- Sulfate – SO 4 2- Carbonate – CO 3 2- Phospate – PO 4 3- Ammonium – NH 4 1+