Formula of a Compound

Transcription

1 Name Formula of a Compound 1. Useful only if it correctly represents the substance. 2. The composition is determined in chemical analysis. 3. The formula then is derived by atomic theory and chemical bonding methods. 4. A chemical formula is a qualitative and quantitative description of the composition of a pure substance, either as element or a compound. Naming Binary Compounds Two types of Binary Compounds A. Combining a metal and a non-metal 1. The metallic element is usually named and written first-this is at times called the cation. Example: KCl -The cation is K, so the name Potassium is written 2. The non-metal, which is called the anion, is made from the root word of the name of the element plus an -ide ending. Cl is chlorine, the root is chlor, then add the -ide ending to write the word chloride. 3. Place both names together: Potassium chloride Problem Section #1 Directions: Write the non-metal ion names for the following 1. Nitrogen 2. Oxygen 3. Sulfur 4. Fluorine 5. Chlorine 6. Bromine

2 Problem Section #2 Directions: Write the correct names for the following Binary Compounds. Formula Ions and charge Name KCl K + Cl - Potassium chloride CaCl 2 AlCl 3 Na 2 S BaS Al 2 S 3 CsF Ba 3 N 2 MgBr 2 Rb 2 O

3 Writing Chemical Formulas 1. Write the symbols to the element with the appropriate charge. 2. Cross over the number that was written as a charge. Problem Section #3 Example Calcium chloride Ca 2+ Cl - becomes CaCl 2 Directions: Write the correct formula for the following Binary Compounds. Compound Name Ions and charge Formula Lithium chloride Li + Cl - LiCl Barium nitride Magnesium bromide Sodium iodide Strontium fluoride Indium phosphide Rubidium sulfide Aluminum selenide Cesium oxide Francium carbide

4 Writing the formula for two non-metal binary compounds With two non-metal binary compounds, the use of prefixes is necessary, for every subscript the compound name must be written with the prefix that coincides with the subscript. Subscript Prefix Subscript Prefix 1 Mono 6 Hexa 2 Di 7 Hept 3 Tri 8 Octa 4 Tetra 9 Nano 5 Penta 10 Deca Example Nitrogen Trioxide No prefix on nitrogen, so no subscript The prefix on oxide is Tri, so the number three will be used as a subscript NO 3 Problem Section #4 Substance Elements Prefixes Subscripts Formula Carbon tetrachloride Carbon None None Chlorine Tetra 4 CCl 4 Dinitrogen monoxide Triphosphorus trifluoride Sulfur dibromide Selenium tetraiodide Sulfur trioxide

5 Problem Section #5 Directions: Write the correct names for the following Binary Non-metal compounds. Formula Element Subscript Prefix Name N 2 O 3 Nitrogen 2 Di Oxygen 3 Tri Dinitrogen trioxide NO P 2 O 4 NO 2 SO 3

6 Problem Section #6 Binary Compounds Write the name to the formula 1. BaCl 2 6. SO 3 2. MgI 2 7. Fr 2 S 3. PF 8. InF 3 4. K 3 N 9. Cs 2 O 5. MgBr KCl Directions: Write the name to the following formulas. 1. Calcium fluoride 2. Barium carbide 3. Gallium oxide 4. Nitrogen trifluoride 5. Trinitrogen dioxide 6. Francium iodide 7. Barium phosphide 8. Decaboron pentoxide 9. Sodium nitride 6

7 Binary Acids Binary Acids start with element Hydrogen followed by a non-metal. The element Hydrogen is renamed Hydro The non-metal root is then written The root then ends with the suffix -ic. Example: HCl Hydrogen and chlorine Hydrogen is rename Hydro The second element chlorine is written in root form, chlor The suffix -ic is now added, chloric Name Hydrochloric Acid Problem Section #7 Directions: Write the names for the following binary compounds. HF HI HBr Naming Binary Acids Take the name and reference it too the elements names Write the charges Cross over the charges Example Hydro chloric Acid Hydro-Hydrogen-H + Chloro-Chlorine-Cl - HCl 1. Hydroiodic Acid 2. Hydrosulfic Acid 7

8 Writing Ternary Compounds A. Made up of three or more different elements usually one element and one polyatomic ion. B. They are made up of metallic elements bonded to polyatomic negative ions. C. The polyatomic ion sheet attached will be of help. D. The following are steps in writing Ternary Compounds together. 1. Write the metallic atom symbol with its charge Example: Na + Example: Sodium sulfite 2. Write the polyatomic ion with its charge in parentheses. Example: (SO 3 ) 2-3. Multiply the metallic atom charge by the subscript on the metallic atom. Example: +1 (x) 1 = 1 (The number of polyatomic ions) 4. Multiply the polyatomic ion charge by the subscript on the metallic atom. Example: 2 (x) 1 = 2 (The number of metallic ions also drop the +/- signs) 5. Place both metallic and polyatomic ions together with subscripts. Example: Na 2 (SO 3 ) 6. Drop the parenthesis if there is no subscript Example: Na 2 SO 3 8

9 Problem Section #8 Directions: Write the correct formulas for the following chemical names. Name Ion Symbol and Charge Formula Aluminum nitrate Al 3+ (NO 3 ) - Al(NO 3 ) 3 Sodium nitrate Mercury (II) cyanide Cadmium (II) silicate Magnesium phosphate Sodium phosphite Lithium tetraborate Iron (III) sulfate Copper (I) thiosulfate Nickel (II) perchlorate 9

10 1. Write the metallic atom name. Ag = Silver Naming Ternary Compounds Example: Ag 2 (C 2 O 4 ) 2. If the element is a transitional element, it will be accompanied by a Roman Numeral. The Roman Numeral will reflect the subscript on the polyatomic ion atom. Silver (I) 3. Write the polyatomic ion name C 2 O 4 = oxalate 4. Write both words Silver (I) oxalate Problem Section #9 Directions: Write the correct name of the compound, when given the formula. The metallic atom name Formula *Roman Numeral if needed/polyatomic Ion Name Cu(C 2 H 3 O 2 ) 2 Copper (II) /acetate Copper (II) acetate Fe 2 (CrO 4 ) 3 Cu 3 PO 4 NH 4 MnO 4 Pb 2 B 4 O 7 NaCN Mg(ClO) 2 Ga(OH) 3 W(SO 4 ) 2 CaC 2 O 4 10

11 All Mixed Up!!!!!!! Directions: Write the name to the following formulas. Formula Binary/Ternary Roman Numeral Name Cr 2 O 3 MgCrO 4 FeCl 3 K 3 PO 4 (NH 4 ) 2 CO 3 CaI 2 BaSO 4 Cu(NO 3 ) 2 Al(CN) 3 CaCO 3 11

12 Directions: Write the formula to the following chemical names. Roman Numeral Formula Binary/Ternary if needed Formula Lithium dichromate Francium bromide Indium nitrite Tungsten (IV) iodide Cobalt (III) sulfite Zinc (II) selenide Silver (I) hydroxide Strontium peroxide 12