An early model of the atom was developed in 1913 by Danish scientist Niels Bohr (1885–1962). The Bohr model shows the atom as a central nucleus containing protons and neutrons with the electrons in circular orbitals at specific distances from the nucleus . These orbits form electron shells or energy levels, which are a way of visualizing the number of electrons in the various shells. These energy levels are designated by a number and the symbol "n." For example, 1n represents the first energy level located closest to the nucleus.
Answer:
Density of a quantity of matter is its mass divided by its volume. The mass of an object depends on the atomic mass of the individual atoms or molecules and the how close the they are compressed together.
Explanation:
Answer:What are the two half reactions that show how many electrons are gained or lost by each species in the reaction:
Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq)?
atoms cannot be created or destroyed in a chemical reaction
