Atoms

Atoms

1. Atoms are the basic units of matter and the defining structure of elements.

   • Atoms are made up of three particles: protons, neutrons and electrons.
     • Protons and neutrons are heavier than electrons and reside in the center of the atom, which is called the nucleus.

2. It contains protons and neutrons, and has most of the mass of the atom.

   • A proton is a small particle with a positive charge found in the nucleus of the atom.
     • An electron is a very small negatively-charged particle found in an atom in the space surrounding the nucleus.

3. Isotopes are atoms of an element with the normal number of protons and electrons, but different numbers of neutrons.

   • Isotopes have the same atomic number, but different mass numbers.
     • The different isotopes of an element have identical chemical properties.

4. Molecules, compounds, and other chemical structures include more than one atom. Sometimes, there are multiples of one particular atom.

   • But – simply knowing how to use a number in this instance is not enough. It is essential to know the proper use of subscripts and superscripts.
     • Atoms often occur as combinations of isotopes. Hydrogen, the simplest gaseous element, has one electron and one proton in all its atoms.

5. The substances in a mixture are separated by the differences in their physical properties, such as their particle size

   • The more different the properties are, the easier it is to separate the substances.

6. Rutherford's model did not completely reimagine Thomson's.