Presentation on theme: "The Structure of Matter"— Presentation transcript:
1 The Structure of Matter Section 1 – Compounds and MoleculesSection 2 – Ionic and Covalent BondingSection 3 – Compound Names and Formulas
2 State StandardsCLE – Distinguish between common ionic and covalent compoundsCLE – Construct chemical formulas for common compoundsCLE.3202.TE.4 – Describe the dynamic interplay among science, technology, and engineering within living, earth-space, and physical systems
3 1 – Compounds and Molecules KEY QUESTIONSWhat holds a compound together?How can the structure of chemical compounds be shown?What determines the properties of a compound?
4 Chemical BondsForces that hold atoms or ions together in a compound are chemical bondsH and O form bonds when water is formed
5 Chemical StructureThe way that atoms are bonded together to make a compound results in chemical structureThis structure can be shown by various modelsExample : Ball and Stick Model
6 Chemical Structure Some models show bond length and bond angles Ball and stickOther models show space occupied by compoundsSpace-filling model ( Figure 2 in Chapter 6 – page 178 )ETHANOL
7 Bonds are like SPRINGS Bonds are flexible and act like springs Bonds can bend, stretch, compress, and twistDo this without breakingTemperature affects this motion ( Kinetic Theory )
8 How Structure Affects Properties Chemical structure determines propertiesNetwork structures form strong solidsQuartz ( network of rigid Si-O-Si bonds )Have to break network to split upSome networks consist of bonded ionsSalt ( NaCl formed from Na+ and Cl- ions )Group 1 elements form cations / Group 17 anionsSome materials are made of separate structuresSugar is a group of single ( the same ) moleculesCan pull out single molecules unlike with a network
9 Attractive Forces Vary Example : H2OWater is liquid at room tempSugar is solid at room tempIndicates that water has weaker attractive forces
10 Attractive Forces Vary Forces between moleculesExample : H2OWater has higher boiling point than H2SIndicates that water has stronger attractive forces
11 1 – Compounds and Molecules KEY QUESTIONSWhat holds a compound together?How can the structure of chemical compounds be shown?What determines the properties of a compound?
12 2 – Ionic and Covalent Bonding KEY QUESTIONSWhy do atoms form bonds?Why do ionic bonds form?What do atoms joined by covalent bonds share?What gives metals their distinctive properties?How are polyatomic ions similar to other ions?
13 Why do Chemical Bonds Form? In general, atoms join to form bonds so that each atom may have a stable electron configurationThey want a full level of valence electrons!!
14 Ionic Bonding Formed from the attraction between ions Ions are formed by transfer of electronsNa and Cl form saltIonic compounds form as networksSolids are the resultIonic compounds dissolved inwater conduct electricity
15 Covalent Bonds These are formed when electrons are SHARED EXAMPLES : O2, Cl2, N2Atoms may share more than one pair of electronsAtoms do not always EQUALLY SHARE electrons
16 Metallic Bonds A type of covalent bond Occurs between metals Electrons move freely betweenmetal atomsMetals are flexible and conduct electricity well because their atoms and electrons can move freely throughout the packed structure
17 Polyatomic IonsActs as a single unit in a compound, like ions that consist of a single atom do ( like Cl, Na )Hydroxide ( OH - )NaOHCarbonate ( CO3 2- )CaCO3Ammonium Sulfate : (NH4)2SO4
18 Polyatomic IonsSome of these are named based on the number of oxygen atoms in compoundNitrate vs NitriteNO3- vs NO2-Chlorate vs. ChloriteClO3- vs ClO2-
19 2 – Ionic and Covalent Bonding KEY QUESTIONSWhy do atoms form bonds?Why do ionic bonds form?What do atoms joined by covalent bonds share?What gives metals their distinctive properties?How are polyatomic ions similar to other ions?
20 3 – Compound Names & Formulas KEY QUESTIONSHow are ionic compounds named?What do the numerical prefixes used in naming covalent compounds tell you?What does a compound’s empirical formula indicate?
21 Naming Ionic Compounds Ionic compounds are named based on the constituent ionsCations ( + ) are named based on the element“calcium”“magnesium”
22 Naming Ionic Compounds Anions ( - ) are altered names of elements“oxide”“chloride”
23 Put ‘Em Together sodium chloride ( NaCl ) magnesium chloride ( MgCl2 ) aluminum oxide ( Al2O3 )
25 Naming Ionic Compounds Charge ( + ) of many transition metals variesFe may have 2+ or 3+Thus, some names show cation chargeiron(III) oxide [common form ]iron(II) oxideCan also see charge in chemical formulasFe2O3 [ Fe3+ since Oxygen is often O2- ]FeO [ both ions have a ‘2’ charge ]
26 Naming Covalent Compounds Numerical prefixes indicate chemical formula when more than atom is involvedExamples:carbon dioxide ( CO2 )silicon dioxide ( SiO2 )boron tetrafluoride ( BF3 )Dinitrogen tetroxide ( N2O4 )N2O4 via Wikepedia.org
27 Empirical FormulasIndicates the smallest whole-number ratio of atoms in a compoundSome are same as chemical formulaHydrogen Peroxide is exception:Chemical Formula – H2O2Empirical Formula – HOFormaldehyde, acetic acid, and glucose have same empirical formula
28 Empirical Formula Molecular Formulas ( had Formula Unit for Ionics ) Emprirical formula can be determined by analyzing mass of each element in a compound
29 3 – Compound Names & Formulas KEY QUESTIONSHow are ionic compounds named?What do the numerical prefixes used in naming covalent compounds tell you?What does a compound’s empirical formula indicate?