Atoms and Subatomic Particles

Subatomic Particles in the Atom

An atom is the basic unit of matter, composed of three main subatomic particles. Each particle has distinct properties and occupies a specific region within the atom.

• Proton: Positively charged particle (+1 charge), located in the nucleus.

• Neutron: Neutral particle (0 charge), also found in the nucleus.

• Electron: Negatively charged particle (-1 charge), found in orbitals surrounding the nucleus.

Example: In a carbon atom, there are 6 protons, 6 neutrons (in the nucleus), and 6 electrons (in orbitals).

Chemical Equations and Balancing

Writing and Balancing Chemical Equations

Chemical equations represent the reactants and products in a chemical reaction. Balancing equations ensures the law of conservation of mass is obeyed, meaning the number of atoms of each element is the same on both sides of the equation.

• Balanced Equation for Formation of Water:

  • Hydrogen gas reacts with oxygen gas to form water.

  • Unbalanced:

  • Balanced:

• Importance of Balancing: Balancing chemical equations is crucial because it reflects the conservation of mass and ensures that the same number of atoms of each element are present before and after the reaction.

Example: In the reaction above, there are 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation.

Solution Concentration: Molarity

Calculating Molarity

Molarity (M) is a measure of the concentration of a solution, defined as the number of moles of solute per liter of solution.

• Formula:

• Example Calculation: What is the molarity of a solution containing 0.5 moles of NaCl in 2 liters of water?

Application: Molarity is used to prepare solutions for chemical reactions and to calculate reactant quantities.

Structure of the Atom

Labeling Parts of the Atom

An atom consists of a central nucleus containing protons and neutrons, with electrons distributed in orbitals around the nucleus.

• Nucleus: Contains protons and neutrons.

• Electron Cloud: Region surrounding the nucleus where electrons are found.

Example: In a diagram, the nucleus is at the center, and electrons are shown in rings or clouds around it.

Additional info: The above notes expand on brief homework questions, providing definitions, equations, and context suitable for General Chemistry students.