Chemistry: Atoms, Elements, and Isotopes

• A chemical symbol represents an element.

Main Parts of an Atom

• Protons

• Neutrons

• Neutrons and protons are larger in size than electrons.

• Neutrons and protons have a larger mass than electrons.

Particles In An Atom

• Protons are found in the nucleus and have a positive charge.

• Neutrons are found in the nucleus and have a neutral charge.

• Electrons are found orbiting the nucleus and have a negative charge.

• The atomic number tells the number of protons and electrons.

• A Tevatron is a particle accelerator (now decommissioned).

• Quarks are fundamental constituents of matter that are found inside protons and neutrons.

• There are six quarks.

• The top quark was hard to find.

• Electrons are so small that they are not considered when determining an element's mass.

• Mass number is equal to the number of protons plus the number of neutrons.

• Mass number is used to identify isotopes.

Isotopes

• Isotopes are identified by their name, atomic number, and number of neutrons.

• Carbon-13 has an atomic number of 6 and 7 neutrons.

• Oxygen-17 has an atomic number of 8 and 9 neutrons.

• Uranium-238 has an atomic number of 92 and 146 neutrons.

• The most common isotope is determined by looking at relative atomic mass.

• The most common isotope of Carbon is Carbon-12

• Dmitri Mendeleev organized the periodic table.

• The modern periodic table is organized by increasing atomic number.

• Electrons move around the nucleus.

• The area where electrons are found/orbit is called electron shells.

• The amount of energy that electrons have is determined by the electron shell location.

• The period number corresponds to the number of electron shells.

• The vertical columns in the periodic table are called groups.

• The first electron shell is filled with 2 electrons.

• The second electron shell is filled with 8 electrons.

Periodic Table

• Magnesium (Mg) has an atomic number of 12, is in period 3, group 2, with 12 protons and 12 electrons.

• Calcium (Ca) has an atomic number of 20, is in period 4, group 2, with 20 protons and 20 electrons.

• Helium (He) has an atomic number of 2, is in period 1, group 18, with 2 protons and 2 electrons.

• Dot diagrams are used to represent valence electrons in an atom.

• New elements are made through nuclear fusion.

Learn about the components of an atom, including protons, neutrons, and electrons, and their charges. Explore isotopes, atomic numbers, and mass numbers. Discover quarks and the role of particle accelerators in understanding matter.