1 / 21

UNIT 2

UNIT 2. Atoms, Ions, Electronic Structure, and Periodic Properties of Atoms and Ions. Ions. Atoms of an element with different numbers of neutrons are called isotopes . Atoms of an element with different numbers of electrons are called ions.

melia
Download Presentation

UNIT 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. UNIT 2 Atoms, Ions, Electronic Structure, and Periodic Properties of Atoms and Ions

  2. Ions • Atoms of an element with different numbers of neutrons are calledisotopes. • Atoms of an element with different numbers of electrons are calledions. • Ions with more electrons than the atom are negatively chargedand calledanions. • Ions with fewer electrons than the atom arepositively chargedand called cations. atomion symbol 23Na name sodium-23 atomic number 11 mass number 23 protons 11 neutrons 12 electrons 11 23Na+ sodium-23 ion 11 23 11 12 10

  3. Ionic Compounds Bonds occur between atoms as a result of interactions among the electrons. • When the interaction is tostrip electrons,the bond is said to be ionic and the entity formed is anionic compound. • Compounds between metals and nonmetals tend to be ionic.(Nonmetals strip electrons from metals to form the anions.) This is a crystal of NaCl. Na+ Cl- NaCl formula unit AND empirical formula

  4. Ionic Compounds • Ionic compounds are made of cations and anions, held together by electrostatic attraction. • Opposite electrical charges attract each other. • Like electrical charges repel each other. • Ionic compounds do not exist as discrete molecules, but as structured aggregates (crystals). • In NaCl, an ionic compound, Na exists as Na+ and Cl exists as Cl-. • The overall charge of the ionic compound is ZERO!

  5. Ion Charges Metal ions typically have a positive charge. • Group 1 metals always have a +1 charge. • Li+, Na+, K+, etc. (H is not a metal.) • Group 2 metals always have a +2 charge. • Mg2+, Ca2+, Ba2+, etc. • Some metal ions can have more than one charge. • We will deal with these later.

  6. Ion Charges Nonmetal ions typically have a negative charge. • Group 17 (or 7A) nonmetals typically have a -1 charge. • F -, Cl-, Br -, etc. • Group 16 (or 6A) nonmetals typically have a -2 charge. • O2-, S2-, Se2-, etc. !!! Knowing what the Groups mean and knowing where the metal/nonmetal boundary is on the periodic table is a BIG help when dealing with ions and ionic compounds !!!

  7. Polyatomic Ions A group of atoms that is covalently bonded yet still has a charge is a polyatomic ion. • NO3- • SO42- • PO43- • ClO2- phosphate ion !!! You are responsible for knowing the names, symbols, and correct charges for the ions listed in Unit 2 of the syllabus !!!

  8. Nomenclature (Naming) • Inorganic compounds • binary ionic compounds • hydrates • binary molecular compounds • acids with anion name of -ide • acids with anion name of -ate or -ite

  9. Naming Binary Ionic Compounds • Name the cation (metal). • Name the anion (nonmetal). • replace the end of the nonmetal with –ide • oxygen becomes oxide • fluorine becomes fluoride • sulfur becomes sulfide • more: NaCl BaI2 Ba3P2 K2S sodium chloride barium iodide barium phosphide potassium sulfide

  10. Naming Metal Ions When More Than One Ion is Possible Two methods • Stock system (Roman numeral is the charge of the cation) • Fe2+ is iron(II) • Fe3+ is iron(III) • Sn2+ is tin(II) • Sn4+ is tin(IV) • Classic (-ic, -ous) system • -ic is for the ion with the higher charge • -ous is for the ion with the lower charge • Fe2+ is ferrous • Fe3+ is ferric • Sn2+ is stannous • Sn4+ is stannic

  11. Naming Binary Ionic Compounds • MgCl2 • CuS • Cu2S • Fe2O3 • Na2O magnesium chloride copper(II) sulfide or cupric sulfide copper(I) sulfide or cuprous sulfide iron(III) oxide or ferric oxide sodium oxide

  12. Writing Formulas for Binary Ionic Compounds • The overall ionic compound MUST BE electrically neutral (have a net charge of 0). • If you do not know the charges of the ions in the compound, you will not be able to write the correct formula for the compound! Write the formula for potassium fluoride. 1. Write the two elements K F 2. Write their charges K+ F- 3. If the charges are equal and opposite, then just put the two elements together: KF Note: there are NO charges in the formula!

  13. Writing Formulas for Binary Ionic Compounds Write the formula for silver oxide. 1. Write the two elements Ag O 2. Write their charges Ag+ O2- 3. When the charges are different, perform a swap: Ag+ O2- Ag2O

  14. Writing Formulas for Binary Ionic Compounds calcium iodide titanium(II) nitride lead(IV) chloride iron(III) oxide CaI2 Ti3N2 PbCl4 Fe2O3

  15. Naming Polyatomic Ions and Polyatomic Oxyanions • Polyatomic ions – memorize list in your syllabus. The names and formulas for other polyatomic ions will be provided to you. (See supplemental ion list on my web site.) • Polyatomic oxyanions • sulfate: SO42- (more O’s, -ate) • sulfite: SO32- (less O’s, -ite) • perchlorate: ClO4- (one more O, per-) • chlorate: ClO3- • chlorite: ClO2- • hypochlorite: ClO- (one less O, hypo-)

  16. Writing Formulas for Binary Ionic Compounds with Polyatomic Ions Write the formula for magnesium sulfate. 1. Write the two ions with their charges. Mg2+ SO42- 2. If the charges are equal and opposite, put the two ions together, being careful NOT to include the charges. MgSO4

  17. Writing Formulas for Binary Ionic Compounds with Polyatomic Ions Write the formula for ammonium sulfate. 1. Write the two ions with their charges. NH4+ SO42- 2. If the charges are not equal and opposite, do the “swap.” NH4+ SO42- (NH4)2SO4 Note the parentheses!

  18. Writing Formulas for Binary Ionic Compounds with Polyatomic Ions sodium hydroxide magnesium hydroxide aluminum hydroxide NaOH Mg(OH)2 Al(OH)3 aluminum phosphate sodium phosphate ammonium phosphate calcium phosphate AlPO4 Na3PO4 (NH4)3PO4 Ca3(PO4)2

  19. Naming Hydrates • Hydrates are ionic compounds with a specific number of water molecules attached. • Name the ionic compound, use the Greek prefix to indicate the number of waters of hydration, and end with the word “hydrate.” • CuSO4•5H2O copper(II) sulfate pentahydrate • BaCl2•2H2O barium chloride dihydrate

  20. Names of Common Chemicals • Baking soda • NaHCO3 (sodium bicarbonate) • uses • in cooking as a leavening agent • as a deodorizer • Table salt • NaCl (sodium chloride) • uses • cooking as a seasoning • preserving meat • throwing over your shoulder for luck

  21. Names of Common Chemicals • Bleach • NaOCl (sodium hypochlorite), or • Ca(OCl)2 (calcium hypochlorite) • uses • well…bleaching • as a sanitizer

More Related