How do I figure out how many valance electrons an element has?

How much heat must be removed from 25.0g of steam at 118.0C in order to form ice at 15C

True or False? Two of the same element chemically combines form a molecule of that element (like O2, I2, N2, H2, etc.)

1.50 * 104 J of energy is transferred thermally into a huge tank filled with liquid water. The water temperature remains constant at 10.0 ∘C during the process. Part ABy how much does the entropy of the water change?

How do classic sedimentary rocks form? Question 2 options: A. Fragments of rock are squeezed and cemented together. B. Plant and animal remains are squeezed and cemented together. C. Solid chemicals in water harden and form rocks. D.

Three isotopes of chromium are chromium-50, chromium-52, and chromium-53. how many neutrons are in each isotope, given that chromium has an atomic number of 24?

How is water different from most liquids? It expands when it freezes. It contains chemical bonds. It has ionic and covalent bonds. It boils when it is heated.

In the thermal decomposition of copper carbonate, the black solid left behind weights less than the original copper carbonate. Why?

The element Oxygen, O, is an example of which of the following? Question 8 options: A compound B molecule C atom D mixture

For the reaction N2 (g) + 3H2 (g) 2NH3 (g), what will happen if more ammonia gas is added?

If Plank's constant is 6.6 x 10 (-34) J/Hz, then what is the approximate frequency of a photon having an energy of 3 x 10 (-19) Joules?