Catalyst If an element has 19 protons… What element is it? What is its mass number? How many neutrons does it have? How many electrons does it have? What is its atomic number? What is its atomic weight? What is the difference between the mass number and the atomic weight? Objective: Describe periodic trends and family properties. Turn in lab report!!!! Have out worksheet. Pick up handouts

Section A.12 – Supplementary Notes I. Valence 1. We’ve spent much of the unit discussing how different elements are organized on the _____________________ according to their __________________. The single most important ______________ property is called _______________. periodic table properties chemical valence

2. Every element’s atomic number indicates the number of _______________ and _______________ in the (neutral) atom. protons electrons

nucleus shells valence electrons outermost a. The electrons “orbit” the ___________________ in ________________. Each electron has a “cloud” or zone that it occupies. b. The _________________ of the atom is the outermost shell of electrons. The valence number is the number of _____________________ in the ___________________ shell. nucleus shells valence electrons outermost

groups valence left right periods electron shells II. Valence and the Periodic Table 1. The ______________, or families, of the periodic table indicate elements with the same properties and _________________, with the valence going up as you move from __________ to ___________. 2. The _______________ on the periodic table correspond to the number of ______________________ on the atom. groups valence left right periods electron shells

3. You can see from the table that the first shell can hold two electrons. The second shell can hold eight. We will mostly be concerned with shells that can hold eight. a.______________________: Atoms desire to have eight electrons in their outermost shells. Many bonds are formed in order to have a complete outermost shell. Some of the elements will form ___________ in order to complete the outermost shell. Octet Rule ions

octet outermost shells lower higher b. Atoms with a full ___________________ in their ______________________ are in a lower energy state than atoms that don’t have an octet. In nature, a ______________ energy state is preferred over a _________________ energy state. octet outermost shells lower higher

alkali metals 1 1 full energy state cations +1 charge 4. Valence of the Groups a. The _____________________ and hydrogen (Group 1A), have a valence of _________, so they lose ______ electron. When they lose one, the shell underneath the outer shell is _________, so they are in their lowest _________________. They often form ______________ with a _______________. Since they need only lose one electron, these elements are highly reactive. alkali metals 1 1 full energy state cations +1 charge

alkaline earth metals cations +2 b. The ____________________________ (Group 2A) have 2 electrons in their outer shell. It’s easier for them to lose two electrons than to gain 6, so this is what they do. They often form _____________ with a _________ charge. alkaline earth metals cations +2

c. The rules for ion formation for transition metals (the B block) are different from the others – this is due to some more complicated rules with the higher electron shells. This is partly why these elements can have multiple ion species (Fe (II) and Fe (III), or Cu (I) and Cu (II)). You’ll learn more about this when you take AP Chemistry.

Aluminum cation +3 4 5 octet d. Elements in group 3A generally lose 3 electrons. Ex: __________________ forms a __________ with a _________ charge. e. Elements in group 4A have ________________ in their outer shell – they act in between and tend to share four electrons in covalent bonds. f. Group 5A elements have ___________ electrons in their outer shell, so they gain 3 electrons to form an _______, either by sharing or gaining to become an ion. Aluminum cation +3 4 5 octet

Oxygen sulfur anions -2 halogens 7 anion -1 Fl- Br- Cl- g. Group 6A have 6 electrons in their valence, so it is easiest to gain 2. Ex: _____________ and ______________ form __________ with a _________ charge. h. The __________________ (group 7A) have _______, so they always gain 1, often forming an __________ with a _________ charge. Ex: ______, ________, ________. Since they need only gain one electron to fill their outer shell, these elements are highly reactive. Oxygen sulfur anions -2 halogens 7 anion -1 Fl- Br- Cl-

noble gases unreactive helium i. The ______________________ (group 8A) are ___________________ because they already have eight -in their outer shell, and are already in their lowest energy state. Note _________________ is an exception – it has a full outer shell with only two electrons. noble gases unreactive helium

How can I use this? Elements in the same columns react the same way If you know CO2 forms, what else forms? Any other column 14 with oxygen, SiO2, GeO2… Any other column 16 with carbon, CS2, CSe2 Any other column 14 with column 16, SiSe2, GeS2 Elements follow a trend down a column If you know the properties of N and As (column 15), P will be in between Trends are less consistent across rows, but melting and boiling point increase with mass.