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Chemistry – PSSA Review – Presentation

Chemistry – PSSA Review – Presentation. Chemistry – PSSA Review. S11.C.1 – Structure, Properties, and Interaction of Matter and Energy. Atoms and subatomic particles. PSSA Eligible Content S11.C.1.1.1. Matter. Anything that has mass and takes up space is known as MATTER .

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Chemistry – PSSA Review – Presentation

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  1. Chemistry – PSSA Review – Presentation

  2. Chemistry – PSSA Review S11.C.1 – Structure, Properties, and Interaction of Matter and Energy

  3. Atoms and subatomic particles PSSA Eligible Content S11.C.1.1.1

  4. Matter • Anything that has mass and takes up space is known as MATTER. • There are two kinds of matter: • Pure Substances – Cannot be broken down • Elements • Examples would include: Fe, Ni, Zn, Hg, Pb, Na, O, He • Compounds • Examples would include: Water, Carbon dioxide, Sugar • Mixtures – Blend of two or more simpler substances • Heterogeneous Mixture - each substance retains own properties • Examples: Pepperoni Pizza, Chocolate Chip Cookies • Homogenous Mixture – uniform composition • Examples: Air, Salt water

  5. Parts of the Atom • ATOM – the basic building block of matter • Composed of smaller subatomic particles:

  6. Parts of the Atom • NUCLEUS – Center of atom; contains protons and neutrons • ELECTRON CLOUD – Space outside of nucleus; Contain electrons • Organized into different energy levels at different distances from the nucleus. Most atoms have more than one energy level.

  7. Structure of the Atom • ATOMIC NUMBER – The number of protons in the nucleus of an atom; No two atoms have the same atomic number! • MASS NUMBER – The number of protons plus the number of neutrons in the nucleus of an atom • ISOTOPES – Atoms of the same element with different numbers of neutrons; Same atomic number but different mass numbers!!

  8. Basic Layout (students do not have this slide) 7 rows = “periods” 18 columns = “groups”

  9. Ions • NEUTRAL ATOM – Number of electrons = number of protons (positive = negative) • Valence Electrons – electrons located in the outermost energy level • ION – Atom that has a charge (has either lost or gained electrons during a reaction) • Cation – Positively charged ion (lost electron(s)) • Anion – Negatively charged ion (gained electron(s))

  10. Particle Structure and Physical Properties S11.C.1.1.2

  11. States of Matter

  12. Properties of Matter • Physical • characteristics of matter that can be observed or measured without changing the identity of the substance. • Ex: Color, texture, phase, malleability, ductility, density, melting point, boiling point • Chemical • Characteristics of matter that describe how substances change in chemical composition. • Ex: flammability, corrosion, decomposition, digestion, respiration

  13. Mass, Volume, Density • Mass • Amount of matter present in a sample of a substance • Metric base unit = Gram, g • Volume • Amount of space occupied by a substance • Metric base unit = Liter, L • Density • Ratio of mass to volume of a substance • D = mass volume

  14. Molecular Shapes • Nonpolar • Even distribution of electrical charge • Polar • Uneven distribution of electrical charge • Dipole (d+, d-)

  15. Effects of Molecular Shape • Nonpolar • Weak attractive forces • Low melting and boiling points • Polar • Strong attractive forces • High melting and boiling points

  16. Chemical Bonding and Chemical Properties S11.C.1.1.3

  17. Key Ideas • COMPOUND – Two or more elements combine chemically • Important characteristics: • Have definite composition • Can be broken down into simpler substances by chemical means • Properties of the compound differ from the properties of the individual elements making it up!

  18. Electrons and Bonding • Electrons • Negatively charged particles • Located in energy levels • Those closest to the nucleus have the smallest amount of energy • ELECTRON CONFIGURATION – Arrangement of electrons around the nucleus of an atom • Each energy level can hold a specific amount of electrons:

  19. Electrons and bonding • Valence electrons are lost, gained, or shared when atoms react with each other to form bonds • CHEMICAL BONDS – forces that hold atoms together • Three types: • IONIC BONDS • COVALENT BONDS • METALLIC BONDS

  20. Ionic Bonds • IONIC BOND – Formed from transfer of electrons from a positively charged ion to a negatively charged ion • OCTET – Atoms seek to have 8 electrons in their outer most level

  21. Covalent Bonds • COVALENT BOND – Formed when two atoms share electrons • OCTET – Seek to have 8 electrons in outer most level • MOLECULE – Structure formed through covalent bonding • LEWIS STRUCTURE – Visually shows covalent bonding and how electrons are shared

  22. Metallic Bonding • METALLIC BOND – Formed when two metals combine • Electron Sea – Group of loosely bound electrons that are shared by all metal cations (+ charged ions)

  23. The Periodic Table S11.C.1.1.4

  24. Basic Layout 7 rows = “periods” 18 columns = “groups”

  25. Properties of Elements • Metals • Solid (except Hg), lustrous, malleable, ductile, good conductors of heat and electricity, tend to lose electrons in chemical reactions • On the left of the steps (except Hydrogen) • Nonmetals • Most are gases, dull color or colorless, brittle when in the solid phase, poor conductors of heat and electricity, tend to gain electrons in chemical reactions • On the right of the steps • Metalloids • Blended properties of metals and nonmetals • On the steps

  26. Special Groups Group 1 = Alkali Metals Group 17 = Halogens Group 2 = Alkaline Earth Metals Group 18 = Noble Gases Groups 3-12 = Transition Metals

  27. Properties of Elements (Slide 2) • Alkali Metals • React vigorously with nonmetals and water • Require special storage • Have 1 valence electron; form +1 ions • Alkaline Earth Metals • Not as reactive as group 1 metals • Have 2 valence electron; form +2 ions • Transition Metals • Hard solids with high melting points • Form colorful ions of varying charge

  28. Halogens • Most reactive nonmetals • 7 valence electrons, -1 ions • Noble Gases • Least reactive of all elements • 8 valence electrons = “Octet”

  29. Gases and gas laws S11.C.1.1.5

  30. Kinetic Molecular Theory GASES: • No definite shape • No definite volume • Molecules are very fart apart • Elastic collisions • Weak intermolecular attraction • Greatly affected by changes in : • Temperature – average kinetic energy of molecules; measured in KELVIN • Pressure – force exerted per unit area; measured in atm, mmHg, kPa

  31. Charles Law • V1 = V2 T1 T2 • T and V are directly proportional.

  32. Boyle’s Law • P1V1 = P2V2 • P and V are inversely proportional

  33. Ideal Gas Law Relates P,V, and T to the number of moles (n) of gas R = 0.08206 Latm/molK n = number of moles = mass/molar mass

  34. Density of Gases Affected by changes in volume d = mass volume If V increases, density will decrease. If V decreases, density will increase.

  35. Reaction Rates S11.C.1.1.6

  36. Chemical Reactions • Chemical Reaction – One or more substance react to produce new, different substances • Reactants  Products • 4 types of chemical reactions: • Synthesis • Decomposition • Single Replacement • Double Replacement

  37. Summary of Reactions ** - Activity Series Required!!

  38. Rate of Reaction • RATE OF REACTION – How fast a reaction takes place • Affected by: • Concentration • Pressure • Temperature • Catalyst • CATALYST – Substance that speeds up a reaction, but it itself is not consumed

  39. Factors Affecting Rates of Reaction

  40. Factors Affecting Rates of Reaction • Temperature – Measure of average kinetic energy in a substance • Increase temperature = Increased rate of reaction • Pressure – Force exerted on a unit area of surface • Little affect on solids, liquids • Increase Pressure = Increased rate of reaction • Concentration – Amount of molecules present per unit volume • Increased Concentration = Increased rate of reaction • Catalyst – Substance that increases rate without being permanently changed or used up

  41. Factors Affecting Rates of Reaction • EQUILIBRIUM – Stable condition in which opposing forces cancel out • REVERSIBLE REACTION – Reactions that can occur in both the forward and reverse directions • LeChatlier’s Principle – Chemical reactions will “work” to relieve changes made to it and get (shift) back into equilibrium • Add more of a substance – shift away from added • Remove substance – shift towards removed • Decrease volume – shift toward side with fewer gas

  42. Chemistry – PSSA Review S11.C.2 – Energy Sources and Transformation of Energy, or Conversion of Energy

  43. Energy Changes in Chemical Reactions S11.C.2.1.2

  44. Chemical Reactions -Energy Diagrams Endothermic Reactions – Require energy (energy is a reactant) Products are at a HIGHER energy than the reactants

  45. Exothermic Reactions – Release energy (energy is a product) Products are at a LOWER energy than the reactants

  46. BOND CHANGES • Breaking bonds is always an ENDOTHERMIC process • Making bonds is always an EXOTHERMIC process

  47. Physical Changes • Change of STATE Heating Curve Cooling Curve

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