Periodic Table & Ion Formation Science 10 Unit 1

Periodic Table: Period 1 Period 2 Period 3 Period 4 Period 5 Period 6 Elements are organized by atomic number (# of protons) Left  Right across each row. Each row is called a period. Period # = # of electron shells in an atom. Period 1 Period 2 Period 3 Period 4 Period 5 Period 6 Period 7

Each column is called a group or family. Elements in the same group have similar chemical properties. Group 1: Alkali Metals Very reactive metals 2: Alkaline Earth Metals Somewhat reactive metals 3-12: Transition Metals 17: Halogens Very reactive non-metals 18: Noble Gases Very unreactive gaseous non-metals Last digit of group # equals the # of valence electrons in the atom. (coloured groups only, not including transition elements) 1 17 18 2 13 14 15 16 3 4 5 6 7 8 9 10 11 12

Periodic Table and Ion Formation Atoms gain and lose electrons to form bonds. The atoms become electrically charged particles called ions. Metals lose electrons and become positive ions (cations). For example, iron, Fe, loses either two (Fe2+) or three (Fe3+) electrons ~

Periodic Table and Ion Formation Non-metals gain electrons and become negative ions (anions). Atoms gain and lose electrons in an attempt to have the same number of valence electrons (electrons farthest from the nucleus) as the nearest noble gas in the periodic table. ~

Ions All atoms want to have a full outer electron shell (valence). Atoms will gain or lose electrons to achieve a full valence. When atoms gain or lose electrons, they become electrically charged. The number of protons (+) is no longer equal to the number of electrons (-). E.g.: Na+1 (Sodium) has 11 protons (+) and only 10 electrons (-) giving it an overall charge of 1+

Ions Metals tend to lose electrons to become postive ions (cations). + 1e- lost Lithium Lithium ion (Li+) Non-metals tend to gain electrons to become negative ions (anions). -2 2e- gained Oxygen Oxygen ion (O2-)

Ions Note: to tell at a glance what kind of ion an element will form, look at the periodic table. Group 1: (Alkali Metals) +1 2: (Alkaline Earth Metals) +2 13: (Aluminum, etc.) +3 14: (Carbon, etc.) ± 4 15: (Nitrogen, etc.) -3 16: (Oxygen, etc.) -2 17: (Halogens) -1

Ions Some metals are multivalent (can form ions in more than one way) i.e.: Iron can lose 2 or 3 electrons to become a 2+ or 3+ ion. On your periodic table, the most common charge is listed on top. Ion Charges Most Common Ion Charges

Mini-Practice Turn to Atoms and Ions Worksheet on the back of your Warm-up - We’ll do examples

Shows all electrons in each energy level around the atom ___ _____ Shows all electrons in each energy level around the atom Electrons in the outermost shell are called valence electrons. Think of the shells as being 3-D like spheres, not 2-D like circles.

Bohr Model of Atomic Structure Shows all electrons in each energy level around the atom. Atomic number = protons Oxygen At. # = 8 8 protons 8p Atomic mass = protons + neutrons 8n Oxygen mass = 16 8 neutrons Note: a neutral atom has no overall charge. protons (+) = electrons (-) Oxygen 8 protons = +8 8 electrons (-8)

Practice: Draw the following Bohr Diagrams

How many electrons fit in each shell? There is a maximum of two electrons in the first shell, eight in the 2nd shell, and eight in the 3rd shell. The period number = the number of shells in the atom. Except for the transition elements, the last digit of the group number = the number of electrons in the valence shell. And 8 electrons in the 3rd shell. It has a stable octet!

Checkpoint Q How many shells would electrons occupy in Sulfur? *Hint* Period number = number of shells 3 4 5 6

Checkpoint Q How many shells would electrons occupy in Sulfur? *Hint* Period number = number of shells 3 4 5 6

Checkpoint Q How many shells would electrons occupy in Kr (Krypton)? *Hint* Period number = number of shells 6 4 5 8

Checkpoint Q How many shells would electrons occupy in Kr (Krypton)? *Hint* Period number = number of shells 6 4 5 8

Checkpoint Q How many valence electrons does magnesium (Mg) have? *Hint* Look at the group number 1 3 2 4

Checkpoint Q How many valence electrons does magnesium (Mg) have? *Hint* Look at the group number 1 3 2 4

Time for some practice!