Chapter 2 Introduction What is matter? What isn’t? What is matter? What isn’t? Matter: Solids,...
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Transcript of Chapter 2 Introduction What is matter? What isn’t? What is matter? What isn’t? Matter: Solids,...
Chapter 2 Introduction
What is matter? What isn’t? Matter: Solids, liquids, gases, plasma Non-matter: light, energy, forces
Think Pair Share
What are Earth materials and why are they important to us?
Rocks, metals/ores, water, etc.
Objectives 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.
Identify the major elements of the Earth’s crust.
“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 Atoms are made of combinations of
protons (+) and neutrons in the nucleus and electrons (-) orbiting around the nucleus.
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)
Assignment:
Turn to page 38 in your book and answer questions 1-6 on a piece of paper to turn in.
Answers can be found in your notes, or from pages 34-38.
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.
Combining Elements
A compound is a substance that is composed of two or more elements that are chemically combined. Water (H2O) is a compound.
Combining Elements
Some elements form bonds when this electron exchange takes place 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.
Combining Elements NaCl is an example of ionic bonding.
Video
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 bonds
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 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)
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/cm3.
Density
Most materials become less dense as state changes from:
solid->liquid->gas. Water is an exception… ICE FLOATS!
Less dense materials float on denser materials.