Bell Work 9/14/17 Complete Electron Configurations worksheet 1-4, 7-9. 11-13

Bell Work 9/18/17 Complete Electron Configurations worksheet

Another Perspective on Electron Configuration https://www.brightstorm.com/science/chemistry/the-atom/orbital-diagrams/ Triboluminescence – light from candy https://youtu.be/9lxhRjxwW0A with explanation https://youtu.be/tW8q_JfmcbU

Valence Electrons Valence electrons: Valence electrons are the electrons in the outermost principal energy level of an atom. These are the electrons that are gained, lost, or shared in a chemical reaction. Elements in a group or family have the same number of valence electrons. © 2013 Pearson Education, Inc. Chapter 3

Predicting Valence Electrons For groups 1 & 2, the group number indicates the number of valence electrons. Group 1 elements have 1 valence electron Group 2 elements have 2 valence electrons In general, transition metals have 2 valence e’s, silver is the exception, it has 1 valence electron For groups 13-18, the last digit indicates the number of valence electrons. Group 14 elements have 4 valence electrons Group 18 elements have 8 valence electrons

Predicting Valence Electrons Exception to the previous trends: Helium only has 2 e’s, so it only has 2 valence e’s.

Valence Electrons of Transition Metals Most transition metals have 2 valence electrons. Except silver He has only 2 valence e’s He 2 Silver has only 1 valence e’

Valence Electrons For the following atoms, identify the number of valence electrons: Helium Phosphorus Calcium Nickel Bromine Oxygen Tin Argon 2 5 7 6 4 8

Electron Dot Structures (EDS)-shows the symbol of the element with the valence e’s represented by dots. Element symbol surrounded by a number of dots equal to the number of valence electrons   Sn    Pb  H  Be    Al   Na  All transition metals have 2 valence e’s, except silver which has 1 valence e’. Zn   Cu   Ag 

Electron Dot Structures (EDS) 18 1 2 13 14 15 16 17

Electron Dot Structures (EDS) for Ions --Use brackets --Metals have no dots-they lose all valence e’s when become an ion. --Nonmetals have 8 dots-they gain enough e’s to have a total of 8. How do you determine the charge?

Learning Check A. X would be the electron dot formula for  A. X would be the electron dot formula for 1) Na 2) K 3) Al   B.  X  would be the electron dot formula for 1) B 2) N 3) V

Solution X would be the electron dot formula for 1) Na 2) K   B.  X  would be the electron dot formula 2) N

Electron Dot Structure (EDS)Practice Write the electron dot structure for the following atoms: Barium Phosphorus Nickel Potassium Silver Argon Aluminum

Ions Ions are charged atoms (or groups of atoms) that have a positive or negative charge. Ions = atoms that have lost or gained electrons Formula for ion includes: symbol, sign, and number Examles: Na+1 Ca+2 I-1 O-2

Positively Charged Ions = Cations Taking away an electron from an atom gives a positive charge because there are now more protons, called a CATION Example: Lithium An atom of lithium will lose 1 e’ to becomes stable (isoelectronic with He) Li ---------------> Li +1 + e’

Negatively Charged Ions = Anions Adding an electron to an atom gives a negative charge because there are now more electrons, called an ANION Example: Fluorine An atom of fluorine will gain 1 e’ to becomes stable (isoelectronic with Ne) F + e’ ---------------> F -1

Formula for Ions-symbol, charge, sign Mg Mg 2+ Neutral atom Atomic number = 12 Protons = 12 Electrons = 12 Equal protons and electrons give no charge Positive ion Atomic number = 12 Protons = 12 Electrons = 10 Two fewer electrons gives an overall charge of 2+

Isotopic Symbol for Ions Write the isotopic symbol for a magnesium ion that has 12 protons, 10 electrons, 11 neutrons. 19

Noble Gases are extremely stable compared to other elements. Noble gases have a full outer energy level- 8 e’s in the outer energy level. Except for helium, there are 2 e’s in outer EL For the other noble gases, there are 8 e’s in the outer EL. When atoms react, they try to achieve the outer configuration of a noble gas-8 electrons in the outer energy level. They become isoelectronic with the nearest noble gas. 20

Octet Rule In chemical reactions, atoms tend to gain, lose, or share electrons so as to have eight valence electrons. This is known as the octet rule.

Octet Rule Metals lose electrons to take on the electron structure of the previous noble gas (go left on the periodic table). In doing so, they form positive ions (cations). Nonmetals tend to gain electrons to take on the electron structure of the next noble gas (go right on the periodic table). In doing so, they form negative ions (anions).

Atoms Forming Stable Ions Sodium can lose a valence electron. After doing so, its core electrons are configured like the noble gas neon. 1s2 2s2 2p6 1s2 2s2 2p6 1s2 2s2 2p63s1 Sodium ion is isoelectronic with neon = Stable Ion

Atoms Forming Stable Ions Chlorine can gain an electron, and in doing so, its electron structure becomes like argon. 1s2 2s2 2p63s23p5 1s2 2s2 2p63s23p6 1s2 2s2 2p63s23p6 Chlorine is isoelectronic with argon = Stable Ion

Predicting Oxidation Number for Metals For groups 1 & 2, the group number indicates the oxidation number (charge) of the ion formed. Group 1 elements acquire a +1 charge. Group 2 elements acquire a +2 charge. Most transition metals acquire a +2 charge, except silver, it acquires a +1 charge. Note most TM’s can have a variety of charges. For group 13 Metals the last digit indicates the oxidation number (charge) on the ion. Group 13 elements acquire a +3 charge.

Predicting Oxidation Number for Nonmetals For groups 15-17, determine the number of electrons needed to be like the nearest noble gases (count boxes going right) Group 15 elements acquire a -3 charge. Group 16 elements acquire a -2 charge Group 17 elements acquire a -1 charge What about group 18, the noble gases? What charge do they acquire?

Oxidation Number for metal and nonmetal elements +1 These occur b/c atoms want to achieve a noble gas e’-configuration. +2 +3 -3 -2 -1

Vocabulary Note: The term “charge” and “oxidation number” can be used interchangeably.

Learning Check Give the number of protons, neutrons, and electrons in: 41Ca +2 20 Write the formula and the EDS for the following ions: Strontium ion Bromine ion Aluminum ion Rubidium ion Arsenic ion

Learning Check Draw the EDS for the following ions: Iodine ion Beryllium ion Nitrogen ion Oxygen ion