Atomic Structure Basics

Atomic Model: The modern atomic model consists of:
- Protons (positive charge) in the nucleus
- Neutrons (no charge) in the nucleus
- Electrons (negative charge) in energy levels around the nucleus
Electron Configuration:
- Electron shells (energy levels) have a maximum number of electrons
- The first shell can hold up to 2 electrons, the second shell up to 8, and so on
- Electron configuration notation: 1s2 2s2 2p6 (example)
Subatomic Particles:
- Protons: positively charged, mass of 1 amu (atomic mass unit)
- Neutrons: no charge, mass of 1 amu
- Electrons: negatively charged, negligible mass

Types of Chemical Bonds:
1. Ionic Bonds: Formed by the transfer of electrons between atoms
  - Cations (positively charged) and anions (negatively charged) attract each other
2. Covalent Bonds: Formed by the sharing of electrons between atoms
  - Polar covalent bonds: unequal sharing of electrons, resulting in a partial charge
  - Nonpolar covalent bonds: equal sharing of electrons
3. Hydrogen Bonds: Weak bonds between hydrogen and highly electronegative atoms (F, O, N)
Bond Properties:
- Bond length: distance between the nuclei of two bonded atoms
- Bond energy: energy required to break a bond
- Bond polarity: difference in electronegativity between bonded atoms

Solid:
- Particles are closely packed and vibrate in place
- Has a fixed shape and volume
Liquid:
- Particles are close together but able to move past each other
- Has a fixed volume but takes the shape of its container
Gas:
- Particles are widely spaced and move freely
- Has neither a fixed shape nor volume
Phase Changes:
- Melting: solid to liquid
- Freezing: liquid to solid
- Vaporization: liquid to gas
- Condensation: gas to liquid

Mole: A unit of measurement, 6.022 x 10^23 particles (atoms, molecules, ions)
Molar Mass: The mass of one mole of a substance, in grams
Empirical Formula: The simplest whole-number ratio of atoms in a compound
Molecular Formula: The actual number of atoms in a molecule
Stoichiometric Calculations:
- Moles of reactants to moles of products
- Mass of reactants to mass of products
- Limiting reagent: the reactant that determines the amount of product formed

Atomic model consists of protons, neutrons, and electrons
Protons have a positive charge and neutrons have no charge, both are found in the nucleus
Electrons have a negative charge and are found in energy levels around the nucleus
Electron shells have a maximum number of electrons, with the first shell holding up to 2 electrons, the second shell up to 8, and so on
Electron configuration notation is used to describe the arrangement of electrons in an atom, for example, 1s2 2s2 2p6

Chemical bonds are formed between atoms through the transfer or sharing of electrons
Ionic bonds are formed by the transfer of electrons, resulting in positively charged cations and negatively charged anions that attract each other
Covalent bonds are formed by the sharing of electrons between atoms, resulting in a molecule
Polar covalent bonds involve unequal sharing of electrons, resulting in a partial charge, while nonpolar covalent bonds involve equal sharing of electrons
Hydrogen bonds are weak bonds between hydrogen and highly electronegative atoms such as fluorine, oxygen, and nitrogen

In a solid, particles are closely packed and vibrate in place, having a fixed shape and volume
In a liquid, particles are close together but able to move past each other, having a fixed volume but taking the shape of its container
In a gas, particles are widely spaced and move freely, having neither a fixed shape nor volume
Phase changes occur when a substance changes from one state of matter to another, such as melting, freezing, vaporization, and condensation

A mole is a unit of measurement, equal to 6.022 x 10^23 particles (atoms, molecules, or ions)
Molar mass is the mass of one mole of a substance, in grams
The empirical formula is the simplest whole-number ratio of atoms in a compound
The molecular formula is the actual number of atoms in a molecule
Stoichiometric calculations involve the mole ratio of reactants to products, and the mass ratio of reactants to products
The limiting reagent is the reactant that determines the amount of product formed