Electronic Structure of Atoms

Electronic Structure of Atoms

• Bohr's model shows electron locations in atoms.
• Electrons orbit the nucleus in shells or energy levels.
• Outer shells have higher energy.
• Each shell holds a specific number of electrons (1st shell = 2, 2nd = 8, 3rd = 18, 4th = 32).
• Shells consist of atomic orbitals (s, p, d, f).
• s-orbitals are spherical, holding up to 2 electrons.
• p-orbitals are dumb-bell shaped, with 3 orbitals (Px, Py, Pz) holding up to 6 electrons.
• Electron configurations show electron arrangement within shells/subshells.
• Lowest energy levels fill first (Aufbau principle).
• Orbitals fill singly before pairing (Hund's rule).
• Paired electrons have opposite spins.

Atomic Orbitals

• Atomic orbitals are regions in the electron cloud.
• They describe the probability of finding an electron.
• Shaped differently, influencing electron behavior.
• Subshells are subsets of main energy levels.
• s, p, d, and f represent the different types of orbitals.

Writing Electron Configurations

• Electron configurations show the arrangement of electrons in an atom.
• Each box represents an orbital.
• Arrows represent electrons with opposite spins.
• The number of electrons is equal to the number of protons in a neutral atom.

Rules for Arranging Electrons

• Fill the lowest energy levels first.
• Fill each sub-level completely before moving to the next.
• Fill each orbital singly before pairing electrons.
• Paired electrons have opposite spins.

Ionic Bonding

• Ionic bonds are strong electrostatic attractions.
• Formed by complete transfer of electrons between positive and negative ions.
• Metal atoms lose electrons, becoming positively charged ions (cations).
• Nonmetal atoms gain electrons, becoming negatively charged ions (anions).
• Ions are arranged in a regular, repeating pattern called a lattice.
• Ionic compounds have high melting and boiling points due to strong attractions between these ions.
• Cations and anions are held in a lattice structure.

Covalent Bonds

• Atoms share electron pairs to form covalent bonds.
• Each atom contributes one electron to the shared pair.
• Dot and cross diagrams show covalent bonds by representing the electrons with dots.
• Shared pairs create the covalent bond, between the atoms represented by circles.
• Covalent bonds hold atoms together in molecules.

Metallic Bonding

• Metallic bonds are strong electrostatic attractions.
• Formed between positive metal ions and delocalized electrons.
• Delocalized electrons are free to move throughout the structure.
• This is why metals are good conductors of heat and electricity.
• Positive metal ions form a lattice, and the delocalized electrons throughout the lattice are free to move.

Trends in the Periodic Table

• Atomic radius decreases across a period.
• Atomic radius increases down a group.
• Electronegativity increases across a period, and down a group.
• Melting points increase across a period to a maximum and then decrease.
• Ionization energy increases across a period and decreases down a group.
• First electron affinity decreases down a group with exceptions

Reactions of Metals

• Many metals react with oxygen, water, and dilute acids.
• Reactivity trends are evident and are related to electron configuration and attraction to the nucleus.
• Reactivity decreases across a period.
• Reactivity increases down a group.
• Formation of oxides depends on reactivity.
• Reactions with acids produce salts and hydrogen gas.

Hydrogen Bonding

• Hydrogen bonds are a special type of intermolecular force.
• Occur when hydrogen is bonded to fluorine, oxygen, or nitrogen.
• Stronger than other dipole-dipole interactions due to pronounced electronegativity differences.
• Hydrogen bonds are stronger than typical dipole-dipole interactions.

This quiz explores the electronic structure of atoms, focusing on Bohr's model and atomic orbitals. It covers concepts such as electron configurations, the filling order of orbitals, and the shapes and capacities of different types of orbitals. Test your understanding of how electrons are arranged around the nucleus!