Atomic Structure and Periodic Table Quiz

Atomic Structure

• Atoms are the smallest unit of matter
• Molecules are a group of atoms bonded together
• Atoms consist of:
  • Protons: Positive charge, located in the nucleus, relative mass 1
  • Neutrons: No charge, located in the nucleus, relative mass 1
  • Electrons: Negative charge, located in shells, relative mass ~0
• Atomic number: Number of protons in an atom
• Mass number: Sum of protons and neutrons
• Isotopes: Atoms of the same element with the same number of protons but different number of neutrons
• Relative atomic mass (Ar): Average mass of isotopes, weighted by their abundance
• Calculate Ar using isotope abundances

The Periodic Table

• Mendeleev arranged elements by properties and atomic mass
• He left gaps predicting undiscovered elements
• Modern periodic table is arranged in order of increasing atomic number
• Groups: Vertical columns; Periods: Horizontal rows
• Metals are on the left-hand side; non-metals are on the right-hand side
• Group number indicates the number of electrons in the outer shell
• Period number indicates the number of electron shells
• Elements in the same group have similar chemical properties

Ionic and Covalent Bonding

• Ionic bonding: Transfer of electrons between metals and nonmetals, forming positive (metal) and negative (non-metal) ions.
• Draw dot-cross diagrams for ionic compounds
• Covalent bonding: Sharing of electrons between nonmetals
• Draw dot-cross diagrams for covalent compounds
• Common ion charges are important to memorize:
  • Group 1, 2, and 3 metals form positive ions
  • Group 5, 6, and 7 non-metals form negative ions
• Specific ions should be known (e.g., charges for given ions)

Group 1 (Alkali Metals)

• React with water to produce hydrogen gas and an alkali
• Reactivity increases down the group
• Use reactivity trends to predict properties of other alkali metals

Group 7 (Halogens)

• Colors, physical states, and reactivity trends (decrease down the group) should be known
• Displacement reactions demonstrate reactivity trends
• Use reactivity trends to predict halogen properties