Elements, Compounds, and Mixtures

• Substances are classified as elements, compounds, or mixtures, based on their composition and bonding.

Elements

• Elements consist of only one type of atom and cannot be broken down into simpler substances.
• Examples of elements include Oxygen (O), Hydrogen (H), and Gold (Au).

Compounds

• Compounds consist of two or more different types of chemically bonded atoms.
• Examples include Water (H₂O), Carbon Dioxide (CO₂), and Sodium Chloride (NaCl).

Mixtures

• Mixtures are combinations of two or more substances that are not chemically bonded.
• The components of mixtures can be separated by physical means.
• Homogeneous mixtures have evenly distributed components, for example, saltwater.
• Heterogeneous mixtures have unevenly distributed components, for example, salad, or oil and water.

Distinguishing Elements, Compounds, and Mixtures

• Elements contain a single type of atom.
• Compounds contain two or more different atoms chemically bonded.
• Mixtures are physical combinations of substances without chemical bonding.

Molecules

• Molecules consist of a group of two or more atoms bonded together, which can be the same or different elements.
• Examples of molecules include O₂ (oxygen), H₂O (water), and CO₂ (carbon dioxide).

Distinguishing Elements, Molecules, and Compounds

• Elements consist of only one type of atom.
• Molecules are a group of atoms bonded together, which can be the same or different types of atoms.
• Compounds are a type of molecule made from different types of atoms chemically bonded together.

Formation of Compounds and Molecules

• Atoms form molecules by sharing or transferring electrons.
• Compounds are formed when atoms of different elements chemically bond, such as H₂O formed from hydrogen and oxygen.

Properties of Compounds vs. Component Elements

• Compounds often exhibit completely different properties from their constituent elements.
• Sodium (Na), a highly reactive metal and Chlorine (Cl), a poisonous gas, combine to form Sodium Chloride (NaCl), common table salt.

Purpose of the Periodic Table

• The periodic table organizes all known elements by atomic number and properties.
• The periodic table helps predict element behaviors and relationships.

Identifying Elements using Atomic Number

• Each element is assigned a unique atomic number, equivalent to the quantity of protons.
• The atomic number determines the element’s position in the periodic table.

Groups and Periods

• Groups are vertical columns in the periodic table; elements in the same group have similar properties.
• Periods are horizontal rows; elements across a period have varying properties but share electron configuration patterns.

Group Names & Element Types

• Alkali metals (Group 1) are highly reactive metals, such as Sodium.
• Alkaline Earth metals (Group 2) are reactive metals, such as Calcium.
• Transition metals are less reactive metals, such as Iron and Copper.
• Halogens (Group 17) are non-metals and highly reactive, such as Chlorine.
• Noble gases (Group 18) are inert gases, such as Helium and Neon.

Real-Life Applications

• Gold (Au) applications: jewelry and electronics.
• Iron (Fe) applications: construction and manufacturing.
• Oxygen (O) applications: breathing and combustion.

Metals vs. Non-Metals

• Metals conduct electricity, are shiny, malleable, and ductile.
• Non-metals are poor conductors, brittle in solid form, and often gases or liquids.

Properties of Alkali Metals, Transition Metals, Metalloids, & Noble Gases

• Alkali Metals: Very reactive, soft metals that conduct electricity.
• Transition Metals: Hard, have high melting points, and conduct electricity.
• Metalloids: Exhibit properties of both metals and non-metals, such as Silicon.
• Noble Gases: Inert, non-reactive, colorless gases.

Distinguishing Atoms, Molecules, & Compounds

• Atoms are the basic units of matter.
• Molecules are combinations of atoms bonded together.
• Compounds are specific molecules made of different types of atoms bonded together.

Drawing Molecular Models

• Molecular models of simple molecules such as O₂, CO₂, and H₂O visually show how atoms bond.

Identifying Constituent Elements

• Carbon (C) and Oxygen (O) are the constituent elements in CO₂.

Atomic Structure

• Subatomic Particles: Protons, Neutrons, and Electrons.
• Protons: Positive charge, and located in the nucleus.
• Neutrons: Neutral charge, and located in the nucleus.
• Electrons: Negative charge, orbit the nucleus.

Atomic Number and Mass

• Atomic Number: The number of protons in the atom.
• Atomic Mass: The sum of protons and neutrons.
• Carbon (C) has an atomic number of 6 (6 protons) and an atomic mass of about 12 (6 protons + 6 neutrons).

Understand the classification of substances into elements, compounds, and mixtures based on their composition and bonding. Explore examples of each, such as oxygen, water, and saltwater. Learn to distinguish between homogeneous and heterogeneous mixtures.