Introduction to Chemistry: States and Properties

• Chemistry is the study of matter and its properties as well as how matter changes

Matter

• Anything that has mass and takes up space is matter.
• Matter exists in three states: solid, liquid, and gas

Solids

• Have a definite shape and volume.
• Solids aren't easily compressible.
• Have a high density.
• Examples include ice, rock, and wood.

Liquids

• Have a definite volume but take the shape of their container.
• Liquids aren't easily compressible.
• Have lower density than solids.
• Examples include water, oil, and blood.

Gases

• Gases have no definite shape or volume, and expand to fill their container.
• Gases are easily compressible.
• Have very low density.
• Examples include air, helium, and steam.

Properties of Matter

• Properties of matter can either be physical or chemical.

Physical Properties

• Physical properties can be observed or measured without changing the composition of the matter.
• Color, density, hardness, melting point, and boiling point are physical properties.

Chemical Properties

• Describe how a substance changes into a new substance.
• Flammability, reactivity, and corrosivity are chemical properties.

Changes of Matter

• Matter can undergo physical or chemical changes.

Physical Changes

• These alter the form or appearance of matter, but don't change its composition.
• Melting, boiling, freezing, and dissolving are physical changes.

Chemical Changes

• Chemical changes will result in the formation of new substances.
• Combustion, oxidation, and decomposition are chemical changes.
• Chemical changes are also known as chemical reactions.

Atoms

• Atoms are the basic building blocks of matter.
• Atoms consist of protons, neutrons, and electrons.

Protons

• Positively charged particles located in the nucleus of the atom.
• The number of protons determines the element.

Neutrons

• Neutral particles located in the nucleus of the atom.
• Neutrons contribute to the mass of the atom but not its charge.

Electrons

• Negatively charged particles that orbit the nucleus in electron shells.
• Electrons determine the chemical properties of the atom.

Elements

• Elements are substances that can't be broken down into simpler substances by chemical means.
• Each element is defined by its atomic number, (number of protons).
• Elements are arranged on the periodic table according to their atomic number and properties.

Compounds

• Compounds are substances consisting of two or more different elements chemically bonded together in a fixed ratio.
• Can be broken down into simpler substances by chemical means.
• The properties of compounds are different from those of their constituent elements.

Molecules

• Molecules are two or more atoms held together by chemical bonds.
• Molecules can be elements or compounds.

Chemical Bonds

• Chemical bonds are the attractive forces that hold atoms together in molecules and compounds.
• Three main types of chemical bonds: ionic, covalent, and metallic.

Ionic Bonds

• Formed by the transfer of electrons between atoms.
• Typically occur between metals and nonmetals.
• Result in the formation of ions (charged particles).
• Ionic compounds are typically crystalline solids at room temperature.

Covalent Bonds

• Formed by the sharing of electrons between atoms.
• Typically occur between nonmetals.
• Create molecules, which can be solids, liquids, or gases at room temperature.

Metallic Bonds

• Formed by the delocalization of electrons among metal atoms.
• Result in good conductivity of electricity and heat.
• Metallic solids, which are typically malleable and ductile, are created.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms and molecules to form new substances.

Reactants

• The substances that react in a chemical reaction.

Products

• The substances that are formed in a chemical reaction.

Chemical Equations

• Chemical equations are symbolic representations of chemical reactions.
• They use chemical formulas to represent reactants and products.
• They must be balanced to obey the law of conservation of mass (the number of atoms of each element must be the same on both sides of the equation).

Stoichiometry

• Stoichiometry is the quantitative study of the relationships between reactants and products in a chemical reaction.
• It's based on the law of conservation of mass and the concept of the mole.

Mole

• The amount of a substance that contains as many elementary entities (atoms, molecules, ions, etc.) as there are atoms in 12 grams of carbon-12.
• One mole is equal to 6.022 x 10^23 entities (Avogadro's number).

Solutions

• Solutions are homogeneous mixtures of two or more substances.
• Consist of a solute and a solvent.

Solute

• The substance that is dissolved in a solution.

Solvent

• The substance that does the dissolving in a solution.
• Usually present in greater quantity.

Acids and Bases

• Acids and bases are important classes of chemical compounds that exhibit characteristic properties.

Acids

• Substances that donate protons (H+) in aqueous solutions.
• Have a pH less than 7.
• Taste sour.
• React with bases to form salts and water.

Bases

• Substances that accept protons (H+) in aqueous solutions.
• Have a pH greater than 7.
• Taste bitter and feel slippery.
• React with acids to form salts and water.

pH

• A measure of the acidity or basicity of a solution.
• pH ranges from 0 to 14.
• A pH of 7 is neutral, a pH less than 7 is acidic, and a pH greater than 7 is basic.

Organic Chemistry

• Organic chemistry is the study of carbon-containing compounds.
• Carbon atoms can form long chains and rings, allowing for a vast diversity of organic molecules.
• Organic compounds are essential to all known life.

Functional Groups

• Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.

Thermodynamics

• Thermodynamics is the study of energy and its transformations.

Energy

• Energy is the capacity to do work or transfer heat.
• Energy can exist in various forms, including kinetic, potential, thermal, and chemical.

Laws of Thermodynamics

• These describe the fundamental principles governing energy transformations.

Chemical Kinetics

• Chemical kinetics is the study of reaction rates and reaction mechanisms.

Reaction Rate

• The speed at which a chemical reaction occurs.
• Influenced by factors such as temperature, concentration, and catalysts.

Catalysts

• Substances that increase the rate of a chemical reaction without being consumed in the process.

This chemistry lesson introduces matter, its three states (solid, liquid, and gas), and their properties. It also covers physical properties such as color, density, melting point, and chemical properties of matter.