ATOMS CHEM-IS-TRY

Atoms are the basic building components of all matter. Atoms are composed of three types of particles: protons, neutrons, and electrons. Protons and neutrons reside in the dense, central, positively-charged nucleus of an atom.

Electrons orbit the nucleus and are located in the region outside the nucleus.

The mass of a single proton, for example, is approximately 1 The mass of a single proton, for example, is approximately 1.67 x 10e-27 kg. The mass of an electron is approximately 9.11 x 10e-31 kg. Mass of a neutron 1.674929 x 10-27 kg

Protons have a positive charge (+) Neutrons are neutral with no charge. Electrons have a negative electric charge (-). In a neutral atom, the number of protons always equals the number of electrons.

# protons = atomic number   # electrons in a neutral atom = number of protons # of neutrons = the difference between the mass number and the atomic number mass number = protons + neutrons

Arrangement of the electrons The maximum number of electron in the first energy level = 2 electrons The maximum number of electron in the second energy level = 8 electrons The maximum number of electron in the third energy level = 18 electrons The maximum number of electron in the fourth energy level 32 electrons The maximum number of electron in the fifth energy = 50 electrons The maximum number of electron in the sixth energy level = 72 electrons The maximum number of electron in the seventh energy level = 98 electrons