By John T. Moore | Richard Langley McGraw-Hill Professional
Updated on Mar 31, 2011
Common Mistakes to Avoid
- Make sure your answer is reasonable. Don't just write down the answer from your calculator.
- Make sure your units cancel in your calculations, leaving the unit you want.
- When balancing nuclear equations, be sure the sum of all mass numbers on the left side of the arrow equals the sum of all mass numbers on the right side. The same will be true of the sums of the atomic numbers.
- When balancing nuclear reactions, be sure you use the atomic number of the unknown and not the mass number to determine the element symbol.
- Make sure that in alpha, beta, gamma, and positron emission the particle being emitted is on the right-hand side of the reaction arrow. In electron capture, the electron should be on the left side of the arrow.
- In half-life problems, don't omit the minus sign. Watch your units.
- In half-life problems, be sure to use the amount of isotope still radioactive as Nt and not the amount decayed.
From 5 Steps to a 5 AP Chemistry. Copyright © 2010 by The McGraw-Hill Companies. All Rights Reserved.