Group (family / column) The Periodic Table Period (row)

Review Period Row of elements. All elements in a period share the same number of energy shells. Group A column of elements. All elements in a group share the same number of valence electrons. They also share characteristics What is Group 1’s family name? What chemical property do they all share?

Classes of Elements in the Periodic Table metal Most elements are classified as either a ______________ or a _____ ___________. Where are these two types generally found? Why is an elements group or position important? The position of an element, relative to other elements in the periodic table, provides a way to predict the physical and chemical properties of the element. Non metal

REVIEW Basic Trends in the Periodic Table As you look across a period or down a group, several properties of elements change in a regular way. Elements are organized by… Every period has… Every group or family has… Atomic number (# of protons) Same number of shells Same number of valence electrons / chemical/physical properties

NAME the Element

Higher level trends Reactivity and Atom Size ALL Periodic Table Trends are Influenced by three main factors:

Why are some elements more/less reactive than other elements? Explain Discuss in groups Which two families are most reactive? Why might they be so reactive? HINT: remember noble gases are STABLE or NONE-REACTIVE

Degree to which the valence shell is full or stable # of Valence Electrons Degree to which the valence shell is full or stable  Think Full House is happy Energy Level Higher energy levels are further away from the nucleus.  Think Distance Charge on nucleus (# protons) More charge pulls electrons in closer. (+ and – attract each other).  Think Greater Electromagnetic force There is a 3rd – blocking or shielding….as well as electronegativity – learn about them in grade 11 4 types of force in nature – strong, weak, electromagnetic, gravity Electromagnetic = law of electric charge – opposites attract, likes repel The electrons are kept in orbit by their attraction to the nucleus (like the moon around earth – gravity) If likes repel, why don’t protons repel each other out of the nucleus? the strong force (greatest of the 4) acts like a glu holding them together

Energy levels have an effect on the GROUP ( FAMILY ) What do they influence? Energy levels have an effect on the GROUP ( FAMILY ) Nuclear charge has an effect on a PERIOD

1) Reactivity and the Outermost Electrons Many of the properties of elements are determined by the ________________ of the ______________ in the ________________ occupied energy level. REVIEW: The electrons in the outermost occupied energy level of an atom are called _______ __________. arrangement electrons outermost Valence electrons

1) Reactivity and the Outermost Electrons Atoms within the same _______________ in the periodic table have the same number of ________________ in their outer energy level. Therefore, elements in a __________ (vertical column or stack) tend to react in a ______________ way. Family or Group electrons group similar

2.) Reactivity and Atom Size The distance from the centre of the _______________ to the _______________ ________________ determines the _______ of an atom. Atoms that need to _______ 1 electron or loose _ electron are _______ reactive. Which two families are most reactive? Why? nucleus outermost electrons size gain 1 most

} Atomic Size Atomic Radius this is half the distance between the two nuclei of a diatomic molecule or the distance from the nuclei to the valence shell } Radius

Atomic Size - Group trends H As we increase the atomic number (or go down a group). . . each atom has another energy level, so the atoms get bigger. Li Na K Rb

down farther larger easier more As you move ________ a group (family - column), there are more shells or energy levels, so the valence electrons are ___________ from the nucleus, and the atom is therefore _________ in size. The farther the valence electron is from the nucleus in metals, the ___________ it is lost, and therefore is _______ reactive. This is because of the electromagnetic attraction with the positive nucleus being smaller farther larger easier more

Remember the Electron has a NEG. charge (-) and the nucleus has a POS Remember the Electron has a NEG. charge (-) and the nucleus has a POS. (+) charge. The greater the distance btw the – and the + regions, the weaker the nucleus’ (+) hold of the electron (-) is. REVIEW: As you move across a period (row) to the _________, atoms gain an additional electron. right

Atomic Size - Period Trends Going from left to right across a period, the size gets smaller. Electrons are in the same energy level. But, there is more nuclear charge (# of protons) Outermost electrons are pulled closer. Na Mg Al Si P S Cl Ar

“Halogens” _____________ or group 17 elements are diatomic, meaning they are found in pairs. The positive nucleus repel one another, so the closer the nucleus are to one another the easier it is to separate them (so that they can form an ionic bond). The easier they separate the more ____________ they are. As you move down the group the distance between nucleus’s increases and additional shells form in-between them, helping to shield the nucleus from one another and decreasing how much they repel one another (making it harder to break them apart). reactive

Isotopes Even though atoms may not be identical (remember: atomic mass was an average of all the variations), they are both atoms of the same ____________ if they have the same number of ____________. Isotope: one of two or more forms of an element that have the _______ number of __________ but a __________ number of _____________. “An element whose atomic mass has changed.” element protons same protons different neutrons

Atomic Mass and Isotopes While most atoms have the same number of protons and neutrons (or close to), some don’t. Some atoms have more or less neutrons than protons. These are called isotopes. An atomic mass number with a decimal is the total of the number of protons plus the average number of neutrons.