Atomic Structure Quiz

Atomic Structure

• Atoms are the smallest unit of matter that can participate in chemical reactions.
• Each atom consists of a nucleus surrounded by a cloud of electrons.
• The nucleus contains protons and neutrons.
• Protons carry a positive charge, neutrons are neutral, and electrons carry a negative charge.
• The number of protons in an atom is called the atomic number.
• This also equals the number of electrons in a neutral atom.
• The mass of an atom is primarily concentrated in the nucleus because protons and neutrons are much heavier than electrons.
• The mass number (nucleon number) represents the total number of protons and neutrons in the nucleus.
• To find the number of neutrons, subtract the atomic number from the mass number.
• Electrons are arranged in energy levels called electron shells.
• The further the shell is from the nucleus, the higher the energy level.
• Electronic configuration describes the arrangement of electrons in an atom.
• Valence electrons are the electrons in the outermost shell of an atom.
• Elements in the same group on the Periodic Table have the same number of valence electrons.

Example: Carbon Atom (C)

• Atomic Number: 6
• Mass Number: 12
• Number of Protons: 6
• Number of Electrons: 6
• Number of Neutrons: 6 (12 - 6 = 6)

Example: Oxygen (O)

• Oxygen has 8 electrons with an electronic configuration of 2, 6.
• 2 electrons are in the first shell, and 6 electrons are in the second shell.

Example: Magnesium (Mg)

• Magnesium has 12 electrons with an electronic configuration of 2, 8, 2.
• 2 electrons are in the first shell, 8 in the second, and 2 in the third shell.