What represents of the number of protons in the nucleus of an element?

PCl3 (g) + Cl2 (g) ⇋ PCl5 (g) Kc = 91.0 at 400 K. What is the [Cl2] at equilibrium if the initial concentrations were 0.24 M for PCl3 and 1.50 M for Cl2 and 0.12 M PCl5.

Whether a material is magnetic or not depends on what

What is the definition of an "atom"?

When do elements absorb energy and enter an excited state?

The element beryllium (Be, atomic number 4 and atomic mass 9) is right above magnesium (Mg, atomic number 12 and atomic mass 24) in the periodic table. How many more electrons does magnesium have than beryllium?

Be sure to answer all parts. Be sure to report your answer to the correct number of significant figures. Determine Kb of the weak base B whose conjugate acid HB + has Ka 6.6 * 10-4.

Compare and contrast each of the following terms. mass and matter

The rate constant of a reaction is 4.7*10-3 s-1 at 25°C, and the activation energy is 33.6 kJ/mol. What is k at 75°C?

What are the pros of using steel?

Cation a has a + 3 charge and is small. cation b has a + 1 charge and is large. which is more likely to occupy negatively charged sites on a clay mineral given equal concentrations in solution? cation a cation b they are the same