Language of Chemistry

Molecules Monatomic = 1 atom

Molecules Molecule = 2 or more nonmetal atoms acting as a unit

Diatomic = molecules of 2 of the same atoms

Triatomic = 3 of the same atoms (O3) Molecules Triatomic = 3 of the same atoms (O3)

Molecular Compounds Composed of molecules Low melting and boiling points Do not conduct electricity in H2O Gases or liquids at room temp 2 or more different nonmetals

Ions Atoms or groups of atoms with a positive or negative charge Form when atoms lose or gain electrons

Cations Any atom or group of atoms with a positive charge It has lost electrons Metals

Cations

Cations Written with a symbol and charge; Na+ Named by element; sodium ion

Atoms or groups of atoms with a negative charge Gained electrons Anion Atoms or groups of atoms with a negative charge Gained electrons Nonmetals

Anion

Written with symbol and charge; Cl- Anion Written with symbol and charge; Cl- Named by elements name plus –ide; chloride ion

Ionic Compounds Composed of ions; cations and anions; metal and nonmetal Solid crystals at room temperature High mp/ bp Neutral Na+ + Cl-  NaCl Conduct electricity In H2O

Chemical Formulas Shows the kinds and numbers of atoms in the smallest representative unit of a substance Symbols show the type of atom Subscripts show how many atoms

Summary What does it mean to say an atom is neutral? What happens to the charge of an atom if an electron is removed? Gained? What is a molecule? What is the difference between molecular and ionic compounds?

Dalton’s Laws

Law of Conservation of Mass Atoms are neither created nor destroyed

Law of Definite Proportions In any sample size of a compound, the mass of the elements are always in the same proportions

Law of Definite Proportions If you take 100g of MgS, you always obtain a ratio of 43.13g Mg / 56.87g S or 0.7584:1.

Law of Multiple Proportions When any two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in small whole number ratios

Law of Multiple Proportions A + B  C A + B  D A in C/ A in D = 5/10 = 1/2

Dalton’s Laws Which law is illustrated below? “In every sample of carbon monoxide, the mass ratio of C:O is 3:4”

Dalton’s Laws Which law is illustrated below? “When C and O form CO and CO2, the different masses of C that combine with the same mass of O is in a ratio of 2:1”

Monatomic ions ions made of one type of atom

Monatomic ions Metallic elements tend to lose electrons to form cations For group A metals, the charge equals the group #

Monatomic ions Nonmetallic elements tend to gain electrons to form anions For group A nonmetals, the charge equals the group # - 8

Monatomic ions Hydrogen is + or - Carbon makes +/- 4 group 8 usually do not make ions

Monatomic ions

Monatomic ions For all other metals (group B metals, others) there is often more than one possible charge

Monatomic ions For group B and other metals, the classical system used to be used for naming

Monatomic ions Now the stock system is used and a roman numeral is used to represent the charge or the charge can be determined by the formula

Monatomic ions Exceptions: Zn2+ ,Cd2+, and Ag+

Monatomic ions

Polyatomic ions tightly bound groups of atoms that act as a unit and carry a charge

Summary What type of ions form from metals? Nonmetals? What is the difference between Cu ,Cu+, and Cu2+? What is an ionic compound?

Formulas for Binary Ionic Compounds The cation and anion must balance each other out by lowest whole number ratios Ex: magnesium nitride

Names for Binary Ionic Compounds Name the cation and the anion If it is a metal with more than one charge, don’t forget the roman numeral

Ternary Ionic Compounds Same rules as binary ionic compounds except you have a polyatomic ion

Molecular Compounds Prefix system used

Molecular Compounds Prefix system used

Molecular Compounds Prefix1element1 prefix2element2 + -ide Except mono is never used on element1

Acids

Acids 6 common acids names and formulas to know

Acids HCl hydrochloric acid HNO3 nitric acid H2SO4 sulfuric acid H2CO3 carbonic acid H3PO4 phosphoric acid HC2H3O2 acetic acid