Presentation on theme: "Chemical Formulas and Equations"— Presentation transcript:
1 Chemical Formulas and Equations Chapter 9 – 2Part 1
2 Chemical FormulasA chemical formula is a shorthand way to use chemical symbols and numbers to represent a substance.A subscript is a number written below and to the right.It tells how many atoms are in this molecule.If there is no subscript, then there is just one atom.C6H12O6Glucose
3 Some Basic RulesWhen you have two elements, you have two words in the nameThe first word is the first element.The second word is the second element.
4 Continued The second word also ends in “IDE”. Like oxygen becomes oxide.
5 Writing Formulas for COVALENT COMPOUNDS Covalent compounds are often composed of nonmetals.The names of many covalent compounds use prefixes.Example: Carbon Dioxide & Dinitrogen monoxideCO2N2O
6 Here are the first ten prefixes: Mono-1Hexa-6Di-2Hepta-7Tri-3Octa-8Tetra-4Nona-9Penta-5Deca-10Prefixes Used in Chemical Names
7 Writing Formulas Covalent Compounds Use the name of compound to write its formulaEx: Carbon DioxideNo prefix on first atom indicates 1 atomThe prefix di indicates 2 oxygen atoms= CO2Prefixes always used on second atom C0 =carbon monoxideWhat is the formula for dinitrogen trioxide?––> N2O3
8 More Practice 1. Dihydrogen monoxide 2. Silicon dioxide 3. Carbon monoxide4. Hydrogen bromide1. H2O2. SiO23. CO4. HBr