Chemistry Chapter 2: Elements and Structure

2.1 The Periodic Table

• The periodic table organizes elements by atomic number and recurring properties.
• Elements in the same group have similar chemical properties due to similar electron arrangements.
• Elements are arranged in periods, reflecting electron shell filling.
• Groups are vertical columns, periods are horizontal rows.
• Metals are generally on the left, non-metals on the right.
• Metalloids sit between metals and non-metals.

2.2 Electronic Structure

• Electrons orbit the nucleus in specific energy levels (shells).
• Each shell can hold a specific number of electrons, following the rule: 2n².
• The outermost shell determines the element's chemical properties.
• Valence electrons are electrons in the outermost shell.
• Electronic configurations describe the arrangement of electrons in shells.

2.3 Metals & Non-Metals

• Metals are good conductors of heat and electricity
• Metals are malleable and ductile (can be hammered into shapes, drawn into wires).
• Non-metals are generally poor conductors of heat and electricity.
• Non-metals are brittle.

2.4 Formation of Ions

• Ions are charged atoms.
• Atoms gain or lose electrons to achieve a full outer shell.
• Metals lose electrons to form positive ions (cations).
• Non-metals gain electrons to form negative ions (anions).

2.5 Ionic Bonding

• Ionic bonds form between oppositely charged ions.
• Electrostatic attraction holds the ions together.
• Ionic compounds are composed of a lattice of ions.

2.6 Ionic Compounds

• Ionic compounds have high melting and boiling points.
• They are often soluble in water.
• They conduct electricity when molten or dissolved in water.

2.7 Covalent Bonding

• Covalent bonds form when atoms share electrons.
• Covalent bonds often occur between non-metals.
• Sharing electrons allows atoms to achieve a full outer shell.

2.8 Types of Covalent Structures

• Covalent bonds can form simple molecular structures (small molecules).
• Covalent bonds can also form giant covalent structures (macromolecules).

2.9 Diamond & Graphite

• Diamond is a giant covalent structure with strong covalent bonds in a tetrahedral arrangement.
• Diamond is very hard and has a high melting point.
• Graphite is a giant covalent structure with layers of carbon atoms in a hexagonal arrangement.
• Graphite is soft and slippery, conducts electricity and has a high melting point.

2.10 Graphene & Fullerenes

• Graphene is a single layer of graphite, extremely strong and conductive.
• Fullerenes are molecules of carbon atoms arranged in closed cages.

2.11 Metallic Bonding

• In metals, valence electrons are delocalized.
• Delocalized electrons are free to move throughout the metallic structure.
• This sea of delocalized electrons holds the positive metal ions together.
• Metallic bonding explains the high melting points, conductivity (heat and electricity) and malleability of metals.