States of Matter States of Matter Notes • There are four states of matter: solid, liquid, gas, plasma.
States of Matter Solids • The particles of a solid are arranged in a definite pattern; thus, a solid has both a definite shape and a definite volume. • Solids are substances with densely packed particles. These particles may be ions, atoms, or molecules. • Solids that have no crystal patterns are called glasses.
States of Matter Solids andLiquids • The atoms in solids vibrate close together at any temperature above absolute zero (2273°C). • The atoms in a liquid can then slide past each other. • While liquids have a definite volume, they take the shape of their container.
States of Matter Gases • In gases, the particles are separated by relatively large distances and move about at extremely hibgh speeds. • Gas particles move freely and independently of each other and travel randomly. • Gases have no definite shape or volume and can expand into any space available, unless they are restrained. • Earth’s gravity keeps the gases in the atmosphere from escaping into space.
States of Matter Gases • Individual particles in a liquid may gain sufficient energy to escape the liquid. • Evaporation, or vaporization, is the process of changing from a liquid to a gas. • When any liquid reaches its boiling point, it vaporizes quickly and becomes a gas. • Sublimation is the slow change of state from a solid to a gas without an intermediate liquid state.
States of Matter Plasma • At temperatures greater than 5000°C, the collisions between particles are so violent that electrons are knocked away from atoms. • Such extremely high temperatures exist in stars, and, as a result, the gases of stars consist entirely of positive ions and free electrons. • Plasmas are hot, highly ionized, electrically conducting gases. • Plasmas can be found in neon tubes, lightening and the stars, including the sun!
States of Matter Changes of State • Solids melt when they absorb thermal energy and their temperatures rise. • When a liquid absorbs thermal energy from the environment, it evaporates. • When a liquid freezes, the same thermal energy is then released back into the environment. • When a gas is cooled, it releases thermal energy in the process of condensation. • Condensation is the change from a gas to a liquid.
Thermal Energy ____ ice melts ____ water vapor condenses to form rain ____ water freezes to make ice ____ water evaporates from a glass
States of Matter Conservation of Matter and Energy • The law of conservation of matter states that “Matter cannot be created or destroyed but can change from one form to another.” • The law of the conservation of energy, also called the first law of thermodynamics, states that energy cannot be created or destroyed but it can be changed from one form to another.
States of Matter Section Assessment 1. Match the following terms with their definitions. ___ crystalline structure ___ glasses ___ evaporation ___ sublimation C A D B A. solids that consist of densely packed atoms arranged at random B.a slow change from a solid to a vapor without an intermediate liquid state C.a solid in which the particles are arranged in regular geometric patterns D. the process of change from a liquid to a gas
States of Matter Section Assessment 3. Identify whether the following processes absorb or release energy into the environment. ___ condensation ___ evaporation ___ melting ___ freezing ___ sublimation A. Absorb energy B.Release energy C.Neither release or absorb B A A B A
What are elements? Matter • The physical world that surrounds you and all living things are composed of matter. • Matter is anything that has volume and mass. • On Earth, matter usually can be found as a solid, liquid, or gas. • All matter is made up of elements.
What are elements? What are Elements? • An element is a substance that cannot be broken down into simpler substances by physical or chemical means. • Currently there are 118 elements on the periodic table. • Ninety-two elements occur naturally on Earth and in the stars. • The other elements have been produced in laboratory experiments.
What are elements? Elements • Each element is identified by a one-, two-, or three-letter abbreviation known as a chemical symbol.
What are elements? What Elements are Most Abundant? • Silicon and oxygen make up 75% of earth’s crust. • Al, Fe, Ca, Na, K, and Mg are also found.
What are elements? Elements are Made of Atoms • Each element has distinct characteristics. • An atom is the smallest particle of an element that has all of the characteristics of that element. • All atoms consist of even smaller particles: protons, neutrons, and electrons.
What are elements? Elements are Made of Atoms • The nucleus, which is made up of protons and neutrons, forms the center of an atom. • A proton (p+) is a tiny particle that has mass and a positive electrical charge. • A neutron (n0) is a particle with about the same mass as a proton, but it is electrically neutral; that is, it has no electrical charge. • Electrons(e-) are located outside the nucleus and have a negative charge. • All atomic nuclei have a positive charge.
An atom of Helium Atomic Number of 2 Atomic Mass of 4 -2 protons -2 electrons (To find neutrons- Mass-Atomic #) 4-2=2! -2 neutrons
What are elements? Elements are Made of Atoms • The number of protons and neutrons in different atoms varies widely. • The mass number is the total number of protons and neutrons. It is the bottom number. • The atomic number is the number of protons only in an atom’s nucleus. This is the top number. • The number of protons is ALWAYS equal to the number of electrons. • You find the number of neutrons by subtracting the number of protons from the mass number.
What are elements? Elements are Made of Atoms • An energy level represents the area in an atom where an electron is most likely to be found. • The mass of an atom depends mostly upon the number of protons and neutrons in its nucleus. • The size of an atom depends upon the number and arrangement of its electrons.
What are elements? Electrons in Energy Levels • Electrons are distributed over one or more energy levels in a predictable pattern. • Each energy level can hold only a limited number of electrons. • The innermost energy level can hold only 2 electrons. • The second energy level can hold up to 8 electrons. • The third energy level can hold up to 18 electrons. • The fourth energy level can hold up to 32 electrons. • Electrons tend to occupy the lowest available energy level.
What are elements? Isotopes • The number of neutrons in the nuclei of an element’s atoms can vary. • Isotopes are atoms of the same element that have different mass numbers and the same chemical properties. • The atomic mass of an element is the average of the mass numbers of the isotopes of an element.
What are elements? Isotopes • The nuclei of some isotopes are unstable and release radiation. • Radioactivity is the spontaneous process through which unstable nuclei emit radiation. • During radioactive decay, a nucleus can lose protons and neutrons, change a proton to a neutron, or change a neutron to a proton. • Because the number of protons in a nucleus identifies an element, decay changes the identity of an element.
What are elements? Section Assessment 1. Match the following terms with their definitions. ___ proton ___ energy level ___ neutron ___ atom A D C B A. a tiny particle that has mass and a positive electrical charge B.the smallest particle of an element that has all of the characteristics of that element C.a tiny particle that has mass and is electrically neutral D. an area of an atom where an electron is most likely to be found
How Atoms Combine Compounds • A compound is a substance that is composed of atoms of two or more different elements that are chemically combined. (Ex. H2O) • Most compounds have totally different properties from the elements of which they are composed. • For most elements, an atom is chemically stable when its outermost energy level is full. • Chemical bonds are the forces that hold the elements together in a compound creating a state of stability.
How Atoms Combine Compounds • One way in which atoms fill their outermost energy levels is by sharing electrons. • A covalent bond is the attraction of two atoms for a shared pair of electrons that holds the atoms together. Covalent Bonds
How Atoms Combine Compounds • A molecule is composed of two or more atoms held together by covalent bonds. • Molecules have no overall electrical charge because the total number of electrons equals the total number of protons.
How Atoms Combine Ions • Sometimes, atoms gain or lose electrons from their outermost energy levels. • A charged particle called an ion is an atom that gains or loses an electron. • In general, an atom in which the outermost energy level is less than half-full tends to lose its valence electrons. • When an atom loses its valence electrons, it becomes positively charged and is indicated by a superscript plus sign.
How Atoms Combine Ions • An atom in which the outermost energy level is more than half-full tends to fill its outermost energy level by adding one or more needed electrons. • Such an atom forms a negative ion which is indicated by a superscript negative sign. • If the outermost energy level is exactly half-full, an atom may form either a positive or negative ion.
How Atoms Combine Ions • Positive and negative ions attract each other. • An ionic bond is the attractive force between two ions of opposite charge. Ionic Bonds • Positive ions are always written first in chemical formulas.
How Atoms Combine Metallic Bonds • In metals, the valence electrons are shared by all the atoms, in a metallic bond.
How Atoms Combine Chemical Reactions • Sometimes, compounds break down into simpler substances. • A chemical reaction is the change of one or more substances into other substances. • Chemical reactions are described by chemical equations.
How Atoms Combine Mixtures and Solutions • A mixture is a combination of two or more components that retain their identities. • When a mixture’s components are easily recognizable, such as soil, it is called a heterogeneous mixture. (Ex. Bag of M & Ms) • In a homogeneous mixture such as coffee, the component particles cannot be distinguished, even though they still retain their original properties.
How Atoms Combine Mixtures and Solutions • A homogeneous mixture is also called a solution. • A solution may be liquid, gaseous, or solid. • Seawater is a liquid solution consisting of water molecules and ions of many elements that exist on Earth. • Air is a solution of gases, mostly nitrogen and oxygen molecules together with other atoms and molecules. • Bronze is a solid solution of copper and tin atoms.
How Atoms Combine Mixtures and Solutions Acids and Bases • Many chemical reactions that occur on Earth involve solutions called acids and bases. • An acid is a solution containing a substance that produces hydrogen ions (H+) in water. • The most common acid in our environment is carbonic acid, which is produced when carbon dioxide is dissolved in water by the following reaction. H2O + CO2®H2CO3
How Atoms Combine Mixtures and Solutions Acids and Bases • The pH scale measures the hydrogen and hydroxide ions in solutions on a scale of 0 to 14, with 7 being neutral. • A solution with a pH reading below 7 is considered to be acidic. • A solution with a reading above 7 is considered to be basic.
How Atoms Combine Section Assessment 1. Match the following terms with their definitions. ___ covalent bond ___ compound ___ ion ___ acid C D A B A. an atom that gains or loses an electron and becomes electrically charged B.a solution containing a substance that produces hydrogen ions in water C.an attraction of two atoms for a shared pair of electrons that hold the atoms together D. a substance that is composed of atoms of two or more different elements that are chemically combined
How Atoms Combine Section Assessment 2. Identify whether the following are acidic, basic, or neutral. ___ Milk ___ Distilled water ___ Rainwater ___ Ammonia ___ Lemon ___ Tomato ___ Antacid A. Acidic B.Basic C.Neutral A C A B A A B
Chapter Resources Menu Chapter Resources Menu Study Guide Section 3.1 Section 3.2 Section 3.3 Chapter Assessment Image Bank
Section 3.1 Study Guide Section 3.1 Main Ideas • The basic building blocks of matter are atoms. Atoms consist of protons, neutrons, and electrons. • Protons have a positive electrical charge, electrons have a negative electrical charge, and neutrons are electrically neutral. Protons and neutrons make up the nucleus of an atom; electrons surround the nucleus in energy levels. • An element is a substance consisting of atoms with a specific number of protons in their nuclei. Isotopes of an element differ by the number of neutrons in their nuclei. Many elements are mixtures of isotopes. • The number of electrons in the outermost energy levels of atoms determines their chemical behavior. Elements with the same number of electrons in their outermost energy levels have similar chemical properties.
Section 3.2 Study Guide Section 3.2 Main Ideas • Atoms of different elements combine to form compounds. • Atoms held together by the sharing of electrons in covalent bonds form molecular compounds. • Ions are electrically charged atoms or groups of atoms. Positive and negative ions attract each other and form ionic compounds. • Acids are solutions containing hydrogen ions. Bases are solutions containing hydroxide ions. Acids and bases can neutralize each other. • A mixture is a combination of components that retain their identities. A solution is a mixture in which the components can no longer be distinguished as separate. Solutions can be liquid, solid, gaseous, or combinations.
Section 3.3 Study Guide Section 3.3 Main Ideas • Matter on Earth exists in three common physical states: solid, liquid, or gaseous. Matter in the universe includes plasma. • Most solids have a crystalline structure. • Liquids are densely packed arrangements of particles. • Gases consist of widely separated, individual particles. Plasmas are hot, highly ionized, electrically conducting gases. • Changes of state involve thermal energy.
Chapter Assessment Multiple Choice 1. Which of the following is NOT about elements? a. They cannot be broken down into simpler substances by physical or chemical means. b. There are 47 naturally occurring elements on Earth and in the stars. c. All matter is made of elements. d. Each element is identified by a chemical symbol. There are 92 elements that occur naturally on Earth and in the stars.
Chapter Assessment Multiple Choice 2. An element’s atomic number represents ____. a. the number of protons in the atom’s nucleus b. the combined number of protons and neutrons in the atom’s nucleus c. the number of neutrons in the atom’s nucleus d. none of the above The combined number of protons and neutrons is the element’s mass number. The number of neutrons can vary among the atoms of an element, creating isotopes.