Chapter 2 Introduction What is matter? What isn’t? What is matter? What isn’t? Matter: Solids, liquids, gases, plasma Matter: Solids, liquids, gases, plasma Non-matter: light, energy, forces Non-matter: light, energy, forces

Think Pair Share What are Earth materials and why are they important to us? What are Earth materials and why are they important to us? Rocks, metals/ores, water, etc. Rocks, metals/ores, water, etc.

Objectives Relate atomic and molecular structure to the traits of matter. Relate atomic and molecular structure to the traits of matter. Understand the states of matter (solid, liquid, gas, plasma) and how matter cycles over time. Understand the states of matter (solid, liquid, gas, plasma) and how matter cycles over time. Identify the major elements of the Earth’s crust. Identify the major elements of the Earth’s crust.

States of matter

“Building Blocks” of Matter  Element: a substance that is made of only one type of atom and cannot be broken down into simpler substances by normal physical or chemical processes.

Atomic Structure  Atom: the smallest particle of an element that has all of it’s characteristics

Atomic Structure Atoms are made of combinations of protons (+) and neutrons in the nucleus and electrons (-) orbiting around the nucleus. Atoms are made of combinations of protons (+) and neutrons in the nucleus and electrons (-) orbiting around the nucleus. Electrons have very little mass. Electrons have very little mass.

Atomic Structure  Atomic Number: the number of protons in the nucleus.

Atomic Structure  Mass Number: the number of protons and neutrons of a specific isotope.  Isotopes have the same number of protons, but different numbers of neutrons Mass Number = (Number of Protons) + (Number of Neutrons )

Atomic Structure  Atomic Mass: the weighted average Mass Numbers of all the isotopes

Combining Elements Some elements are quite content to remain alone, but most will attempt to combine with other elements to form the various the common objects and substances we see every day. Some elements are quite content to remain alone, but most will attempt to combine with other elements to form the various the common objects and substances we see every day.

Combining Elements A compound is a substance that is composed of two or more elements that are chemically combined. A compound is a substance that is composed of two or more elements that are chemically combined. Water (H2O) is a compound. Water (H2O) is a compound.

Combining Elements Some elements form bonds when this electron exchange takes place Some elements form bonds when this electron exchange takes place Covalent bonds form when atoms share electrons, such as H2O. Covalent bonds form when atoms share electrons, such as H2O. Ionic bonds form when electrons are exchanged, creating charged atoms called ions. Table salt (NaCl) is an example. Ionic bonds form when electrons are exchanged, creating charged atoms called ions. Table salt (NaCl) is an example.

Combining Elements NaCl is an example of ionic bonding. NaCl is an example of ionic bonding.

Metallic bonds  Metallic bonds are strong and found in metals, such as copper. Electrons are free to move from one positive ion to another. Flowing electrons = conduction of electric current and heat  Metallic bonding gives metals special properties that make metals valuable as Earth resources. Metals may be mixed into minerals/rocks. Minerals which contain metals are called ores.

Mixtures Mixtures occur when compounds and elements mix together but do NOT combine chemically. Mixtures can be physically separated. Mixtures occur when compounds and elements mix together but do NOT combine chemically. Mixtures can be physically separated. The mixture is heterogeneous if each component of mixture retains its own properties. EXAMPLE: oil and water The mixture is heterogeneous if each component of mixture retains its own properties. EXAMPLE: oil and water

Homogeneous mixtures Homogeneous mixtures are also known as solutions. The properties of the components may be different from the properties of the mixture. EXAMPLE: salt and water (a liquid solution formed when salt dissolves in water) Homogeneous mixtures are also known as solutions. The properties of the components may be different from the properties of the mixture. EXAMPLE: salt and water (a liquid solution formed when salt dissolves in water)

Density  Density is a property of matter.  Density: A measure of the mass of an object divided by its volume. The unit of measure is frequently g/mL or g/cm 3.  Most materials become less dense from as state changes from solid->liquid->gas. Water is an exception… ICE FLOATS!  Less dense materials float on denser materials.

Handout notes and worksheet on density… Handout notes and worksheet on density…