Units of Measurement: Metric and SI Systems

Units of Measurement

• Measurements are used in everyday life.
• Units are used in the metric and International System of Units (SI) to specify measurements.
• The English system is used in the United States.
• The metric system is used in most countries.
• The SI system is used by scientists and is based on the metric system.

Measurements

• Length is measured using a meter stick in both the metric and SI systems.
• Volume is measured in liters (L) in the metric system and cubic meters (m³) in the SI system.
• Mass is measured in grams (g) in the metric system and kilograms (kg) in the SI system.
• Temperature is measured in Celsius (°C) in the metric system and Kelvin (K) in the SI system.
• Time is measured in seconds (s) in both the metric and SI systems.

Mass

• Mass of an object is the amount of matter in it.
• Ionic compounds are represented using their Empirical Formulas.

Chemical Formulas

• Molecular Formula gives the actual number of atoms of each element in a molecule.
• Structural Formula shows how atoms in a molecule are bonded together.
• Molecular Models include Ball-and-Stick Model and Space-Filling Model.

Atomic Level View of Elements and Compounds

• Atomic Elements are elements whose particles are single atoms.
• Formula Mass is the sum of the masses of the atoms in a single molecule or formula unit.
• Molar Mass is the mass of one mole of a substance, expressed in g/mol.

Chemical Reactions

• A chemical reaction is a process that transforms one set of substances into another.
• Reactants are substances initially involved in a chemical reaction.
• Products are substances produced by a chemical reaction.

Chemical Equations

• Chemical Equation is a shorthand way to describe a chemical reaction.
• Net Ionic Equation is the chemical equation that shows only the ions that participate in the reaction.

Chemical Bonds

• Chemical Bonds hold atoms together in compounds.
• Chemical bonds form due to attractions between protons and electrons of bonded atoms.
• Chemical bonds lower the potential energy between charged particles in atoms.

Types of Chemical Bonds

• Ionic Bonds form when electrons are transferred, resulting in oppositely charged ions that attract each other.
• Covalent Bonds form when atoms share electrons.
• Metallic Bonds form between metal atoms.

Intermolecular Forces

• Intermolecular Forces (IMF) are weak attractions between molecules.
• IMF affect the rate and outcome of chemical reactions.

Types of Intermolecular Forces

• London Dispersion Forces are weak interactions due to momentary changes in electron density in a molecule.
• Dipole-dipole interactions are attractive forces between permanent dipoles of polar molecules.
• Hydrogen Bonding is a strong type of dipole-dipole interaction that occurs between molecules containing hydrogen bonded to oxygen, nitrogen, or fluorine.

Intermolecular Hydrogen Bonding

• Intermolecular hydrogen bond occurs between two molecules with hydrogen located between two electronegative groups.

Explore the essential units of measurement used in everyday life, focusing on the metric and SI systems. This quiz covers length, volume, mass, temperature, and time, providing insights into how different systems are employed globally and scientifically.