Presentation on theme: "Objectives Vocabulary"— Presentation transcript:
1Objectives Vocabulary What are elements?ObjectivesI can describe the particles within atoms and diagram the structure of atoms.I can use the periodic table to relate the energy levels of atoms to the chemical properties of elements.I can define the concept of isotopes.Vocabularyenergy levelvalence electronisotopeatomic massradioactivityelementatomnucleusprotonneutronatomic numbermass numberelectron
2What are elements?What are elements?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.
3Elements All matter is made of substances called elements. What are elements?ElementsAll matter is made of substances called elements.An element cannot be broken down into simpler substances by physical or chemical means.Ninety-two elements occur naturally on Earth and in the stars.Other elements have been produced in laboratory experiments.
5Elements are Made of Atoms What are elements?Elements are Made of AtomsEach 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.
6Elements are Made of Atoms What are elements?Elements are Made of AtomsThe 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.
7The Atomic number is the number of protons in an atom’s nucleus. What are elements?The Atomic number is the number of protons in an atom’s nucleus.The mass number (or Atomic weight) is the combined number of protons and neutrons.
8Elements are Made of Atoms What are elements?Elements are Made of Atoms
9Elements are Made of Atoms What are elements?Elements are Made of AtomsSurrounding the nucleus of an atom are smaller particles called electrons.An electron (e–) has little mass, but it has a negative electrical charge that is the same value as the positive charge of a proton.An atom has an equal number of protons and electrons which produces an atom that has no overall charge.
10Elements are Made of Atoms What are elements?Elements are Made of AtomsAn 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.
11Electrons in Energy Levels What are elements?Electrons in Energy LevelsEach 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.
12Electrons in Energy Levels What are elements?Electrons in Energy LevelsValence electrons are the outermost electrons in an atom.The number of electrons in the outermost energy level determines the chemical behavior of the different elements.Elements with the same number of valence electrons have similar chemical properties.
13Electrons in Energy Levels What are elements?Electrons in Energy LevelsSodium (Na) atoms, with just one valence electron, are highly reactive metals, which means that they combine easily with other elements.
14Electrons in Energy Levels What are elements?Electrons in Energy LevelsElements such as helium (He), neon (Ne), and argon (Ar) are inert, which means that they do not easily combine with other elements.This is because they have full outermost energy levels.
15What are elements?IsotopesThe 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.The atomic mass of an element is the average of the mass numbers of the isotopes of an element.
16What are elements?IsotopesThe 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, radioactive decay can change the identity of an element.
17What Elements are Most Abundant? What are elements?What Elements are Most Abundant?The two most abundant elements in the universe are hydrogen and helium.
18What Elements are Most Abundant? What are elements?What Elements are Most Abundant?The percentages of elements in Earth’s crust differ from the percentages in the universe.
19What are elements?Section Assessment1. Match the following terms with their definitions.___ proton___ energy level___ neutron___ atomADCBA. a tiny particle that has mass and a positive electrical chargeB. the smallest particle of an element that has all of the characteristics of that elementC. a tiny particle that has mass and is electrically neutralD. an area of an atom where an electron is most likely to be found
20What are elements?Section Assessment2. What arrangement of electrons would you expect to find in an iron (Fe) atom?____ first energy level____ second energy level____ third energy level____ fourth energy level2816
21What are elements?Section Assessment3. Identify whether the following statements are true or false._______ The number of protons can differ from atom to atom in the same element._______ Oxygen and silicon are the most abundant elements in the universe._______ Elements with the same number of valance electrons have similar properties.truefalse
23Objectives Vocabulary How Atoms CombineObjectivesDescribe the chemical bonds that unite atoms to form compounds.Relate the nature of chemical bonds that hold compounds together to the physical structures of compounds.Distinguish among different types of mixtures and solutions.Vocabularycompoundchemical bondcovalent bondmoleculeionionic bondchemical reactionsolutionacidbase
24How Atoms CombineCompoundsA compound is a substance that is composed of atoms of two or more different elements that are chemically combined.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.
25Compounds Covalent Bonds How Atoms CombineCompoundsCovalent BondsOne 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.
26Compounds Covalent Bonds How Atoms CombineCompoundsCovalent BondsA 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.
27Compounds Covalent Bonds How Atoms CombineCompoundsCovalent BondsMolecules are represented in chemistry by chemical formulas that include the symbol for each element followed by a subscript number that stands for the number of atoms of that element in the molecule.If there is only one atom of an element, no subscript number follows the symbol.A molecular compound is a compound comprised of molecules.
28Compounds Polar Molecules How Atoms CombineCompoundsPolar MoleculesWhen atoms in a covalent bond do not share electrons equally, they form polar bonds.Polar bonds have a positive end and a negative end.The overall shape of a molecule indicates whether it is polar.
29How Atoms CombineIonsSometimes, 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.
30How Atoms CombineIonsAn 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.
31Ions Ionic Bonds Positive and negative ions attract each other. How Atoms CombineIonsIonic BondsPositive and negative ions attract each other.An ionic bond is the attractive force between two ions of opposite charge.Positive ions are always written first in chemical formulas.
32How Atoms CombineIonsIonic BondsWith an ionic compound, the net electrical charge of the compound is zero.Ionic compounds are compounds formed by ionic bonding.
33How Atoms CombineMetallic BondsIn metals, the valence electrons are shared by all the atoms, not just by adjacent atoms.The positive ions of the metal are held together by the negative electrons between them.This type of bond, known as a metallic bond, allows metals to conduct electricity easily because the electrons can move freely throughout the entire solid metal.
34How Atoms CombineChemical ReactionsSometimes, 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.A chemical equation must be balanced by showing an equal number of atoms for each element on each side of the equation.
35Mixtures and Solutions How Atoms CombineMixtures and SolutionsA 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.In a homogeneous mixture such as coffee, the component particles cannot be distinguished, even though they still retain their original properties.
36Mixtures and Solutions How Atoms CombineMixtures and SolutionsA 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.
37Mixtures and Solutions How Atoms CombineMixtures and SolutionsAcids and BasesMany 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
38Mixtures and Solutions How Atoms CombineMixtures and SolutionsAcids and BasesThe 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 ® H2CO3Some of the carbonic acid molecules in the water dissociate, or break apart, into hydrogen ions and bicarbonate ions, as represented by the following equation. H2CO3 ® H+ + HCO2–
39Mixtures and Solutions How Atoms CombineMixtures and SolutionsAcids and BasesBases produce hydroxide ions (OH–) in solution.A base can neutralize an acid by combining with hydrogen ions of the acid to form water through the following reaction. H+ + OH– ® H2OThe pH scale measures the hydrogen and hydroxide ions in solutions on a scale of 0 to 14, with 7 being neutral.
40Mixtures and Solutions How Atoms CombineMixtures and SolutionsAcids and BasesThe 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.
41How Atoms CombineSection Assessment1. Match the following terms with their definitions.___ covalent bond___ compound___ ion___ acidCDABA. an atom that gains or loses an electron and becomes electrically chargedB. a solution containing a substance that produces hydrogen ions in waterC. an attraction of two atoms for a shared pair of electrons that hold the atoms togetherD. a substance that is composed of atoms of two or more different elements that are chemically combined
42How Atoms CombineSection Assessment2. Identify whether the following are acidic, basic, or neutral.___ Milk___ Distilled water___ Rainwater___ Ammonia___ Lemon___ Tomato___ AntacidACBA. AcidicB. BasicC. Neutral
43Section Assessment 3. Describe the following chemical equation: How Atoms CombineSection Assessment3. Describe the following chemical equation:S + O2 ® SO2One sulfur atom reacts with one oxygen molecule to yield one molecule of sulfur dioxide.
45Objectives Vocabulary I can describe the states of matter on Earth. I can relate the role of thermal energy to changes of state in matter.I can balance chemical equations.Vocabularycrystalline structureglassevaporationsublimationplasmacondensation
46States of MatterSolidsSolids are substances with densely packed particles, which may be ions, atoms, or molecules, depending upon the substance.The particles of a solid are arranged in a definite pattern; thus, a solid has both a definite shape and a definite volume.Most solids have a crystalline structure, in which the particles are arranged in regular geometric patterns.
47States of MatterSolidsCrystals form symmetrical solid objects with flat faces and straight edges between faces.The angles between the faces depend upon the internal arrangement of the particles.
48States of MatterLiquidsThe atoms in solids vibrate at any temperature above absolute zero (-273°C).These thermal vibrations increase with increasing temperature.At the melting point of a material, vibrations break the forces holding the solid together and the substance becomes liquid.While liquids do not have their own shape, they do have definite volume.
49States of MatterGasesIndividual particles in a liquid may gain sufficient energy to escape the liquid.Evaporation - process of changing from a liquid to a gas.When any liquid reaches its boiling point, it vaporizes quickly and becomes a gas.Sublimation - change of state from a solid to a gas without going through the liquid state.
51States of MatterPlasmaAt 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.
52States of MatterChanges of StateSolids 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.
53Conservation of Matter and Energy States of MatterConservation of Matter and EnergyThe law of conservation of matter & energy- matter & energy cannot be created or destroyed but can change from one form to another.
54Balancing Chemical Equations ___H2 + ____ O2 ____ H2O 2 H2 + 1 O2 2 H2OThe Law of Conservation of Matter means that there will be equal numbers of each type of element on both sides of the equation.
55States of MatterSection Assessment1. Match the following terms with their definitions.___ crystalline structure___ glasses___ evaporation___ sublimationCADBA. solids that consist of densely packed atoms arranged at randomB. a slow change from a solid to a vapor without an intermediate liquid stateC. a solid in which the particles are arranged in regular geometric patternsD. the process of change from a liquid to a gas
56States of MatterSection Assessment2. What are two examples of matter in the plasma state that you have seen?Lightning and the matter inside a neon tube are in the plasma state.
57States of MatterSection Assessment3. Identify whether the following processes absorb or release energy into the environment.___ condensation___ evaporation___ melting___ freezing___ sublimationBAA. Absorb energyB. Release energyC. Neither release or absorb
59Chapter Resources Menu Study GuideSection 3.1Section 3.2Section 3.3Chapter AssessmentImage BankChapter Resources Menu
60Section 3.1 Study GuideSection 3.1 Main IdeasThe 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.
61Section 3.2 Study GuideSection 3.2 Main IdeasAtoms 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.
62Section 3.3 Study GuideSection 3.3 Main IdeasMatter 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.
63Multiple Choice 1. Which of the following is NOT about elements? Chapter AssessmentMultiple Choice1. 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.
64Multiple Choice 2. An element’s atomic number represents ____. Chapter AssessmentMultiple Choice2. An element’s atomic number represents ____.a. the number of protons in the atom’s nucleusb. the combined number of protons and neutrons in the atom’s nucleusc. the number of neutrons in the atom’s nucleusd. none of the aboveThe 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.
65Multiple Choice 3. Which is the most abundant element in the universe? Chapter AssessmentMultiple Choice3. Which is the most abundant element in the universe?a. oxygen c. ironb. helium d. hydrogenHydrogen makes up about 93.5% of all matter in the universe. It is followed by helium at 6.3%.
66Chapter AssessmentMultiple Choice4. Which is the most abundant element in Earth’s crust?a. hydrogen c. oxygenb. silicon d. aluminumOxygen makes up of Earth’s crust. It is followed by silicon (27.7%), aluminum (8.1%), and iron (5.0%).
67Multiple Choice 5. Which of the following is a molecule? Chapter AssessmentMultiple Choice5. Which of the following is a molecule?a. argon c. nitrogenb. water d. uraniumArgon, nitrogen, and uranium are elements.
68Chapter AssessmentShort Answer6. What condition is necessary for matter to be in a plasma state?The temperature must be greater than 5000ºC. At temperatures this high, the collisions between particles are so violent that electrons are knocked away from atoms.
69Short Answer 7. What three forms can a solution take? Chapter AssessmentShort Answer7. What three forms can a solution take?A solution may be liquid, gaseous, or solid.
70Chapter AssessmentTrue or False8. Identify whether the following statements are true or false.______ A pH value of 11 would indicate an acid.______ Ions are atoms that either lost or gained an electron.______ Apple juice is an example of a solution.______ In a polar bond, electrons are shared equally.______ Two negative ions will join to create an ionic bond.falsetrue
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