Elements Answers

All atoms of the element potassium have 19 protons. One of the most stable types of potassium atoms has the mass number 39.

Uranium is an element that is often used in nuclear power plants. Uranium atoms are very large, and the substance can be dangerous if it is not carefully contained.

The simple model below is a neutral magnesium (Mg) atom with the element’s most common mass number.

If we have a sample of silicon (Si) atoms that has 14 protons, 14 electrons, and 18 neutrons

One isotope of sodium has 11 protons and 7 neutrons. What is the mass number of this isotope?

All large radioactive atoms decay into smaller atoms by releasing alpha particles. Each alpha particle has 2 protons, 2 neutrons, and 0 electrons. The table below describes several neutral, low-mass atoms.

What is the number at the end of an isotope’s name?

Which are different forms of an element that have different numbers of neutrons?

Which describes an atom that has fewer neutrons than protons and more electrons than protons?

What can be added to an atom to cause a nonvalence electron in the atom to temporarily become a valence electron?