1. CHEM 1405: Introductory Chemistry Houston Community College Dr. Laura Jakubowski Chapter 3 – Matter and Energy Textbook “Introductory Chemistry: Concepts and Critical Thinking” Seventh Edition by Charles H. Corwin © 2014 Pearson Education, Inc.

2. Physical States of Matter Matter is defined as a substance that has mass and occupies volume It exists in one of three physical states: Solid – particles are tightly packed, held in rigid positions Liquid – particles are loosely packed, free to move around Gas – particles are widely spaced apart and uniformly distributed 2 © 2014 Pearson Education, Inc.

3. Physical States of Matter 3 © 2014 Pearson Education, Inc. Every substance can exist as a solid, liquid, or gas With increasing temperatures: Solid ice melts to liquid water at 0 °C Liquid water vaporizes to steam at 100 °C With decreasing temperatures: Steam condenses back to water at 100 °C Water freezes back to ice at 0 °C

4. Physical States of Matter The direct change of state from a solid to a gas is called a sublimation Dry ice sublimes directly from a solid to a gas (carbon dioxide) The direct change of state from a gas to a solid is called a deposition Opening a freezer door causes deposition of frost inside without a trace of liquid water 4 © 2014 Pearson Education, Inc.

5. Change of Physical State State the term that applies to each of the following physical changes Snow changes from a solid to a liquid Gasoline changes from a liquid to a gas Dry ice changes from a solid to a gas A refrigerant changes from a gas to a liquid Water changes from a liquid to a solid Iodine vapor changes from a gas to a solid 5 © 2014 Pearson Education, Inc. Label as solid, liquid or gas:

6. Change of Physical State State the term that applies to each of the following physical changes Snow changes from a solid to a liquid  melting Gasoline changes from a liquid to a gas  vaporizing Dry ice changes from a solid to a gas  sublimation A refrigerant changes from a gas to a liquid  condensation Water changes from a liquid to a solid  freezing Iodine vapor changes from a gas to a solid  deposition 6 © 2014 Pearson Education, Inc. Gas Liquid Solid Label as solid, liquid or gas:

7. Elements, Compounds, and Mixtures A sample of matter may be a mixture or it may be a pure substance Mixtures are composed of more than one substance and can be physically separated into its component substances A heterogeneous mixture – DOES NOT have uniform properties throughout A homogeneous mixture – DOES have uniform properties throughout 7 © 2014 Pearson Education, Inc. Sand in water is a heterogeneous mixture Table salt in water is a homogeneous mixture

8. Elements, Compounds, and Mixtures A homogeneous mixture of two or more metals is known as an alloy 10K, 14K, 18K jewelry may contain varying amounts of gold, silver and copper Pure substances are composed of only one substance and cannot be physically separated A substance has definite composition and constant properties A compound CAN be broken down into elements by an ordinary chemical reaction An element CANNOT be broken down further by a chemical reaction 8 © 2014 Pearson Education, Inc. Sugar is a compound Mercury is an element

9. Classification of Matter 9 © 2014 Pearson Education, Inc.

10. Element, Compound, or Mixture Classify each of the following samples as an element, compound, homogeneous mixture, or heterogeneous mixture a)Copper metal – cannot be broken down by a chemical change b)Copper oxide – copper which has reacted with oxygen c)Malachite ore – can be mined from earth, contains copper d)Bronze – alloy consisting of copper and tin e)Mercury liquid – cannot be broken down by a chemical change f)Mercury oxide – when heated, gives mercury and oxygen gas g)Dental alloy – composed of mercury and silver h)Cinnabar ore – mined from Spain and Italy, contains mercury 10 © 2014 Pearson Education, Inc.

11. Element, Compound, or Mixture Classify each of the following samples as an element, compound, homogeneous mixture, or heterogeneous mixture a)Copper metal – b)Copper oxide – c)Malachite ore – d)Bronze – e)Mercury liquid – f)Mercury oxide – g)Dental alloy – h)Cinnabar ore – 11 © 2014 Pearson Education, Inc. element compound heterogeneous mixture homogeneous mixture element compound heterogeneous mixture homogeneous mixture

12. Names and Symbols of the Elements There are over 100 elements, 81 of which are stable and occur naturally Only 10 elements account for 95% of the mass of Earth’s crust, water, and atmosphere Oxygen is the most abundant element, it constitutes 21% of the atmosphere and it combines with hydrogen to form water 12 © 2014 Pearson Education, Inc.

13. Names and Symbols of the Elements The elements oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus account for over 99% of the mass of the human body Other trace elements are also essential to life – iron is necessary to bind oxygen to hemoglobin in the blood 13 © 2014 Pearson Education, Inc.

14. Names and Symbols of the Elements Each element has a unique name Hydrogen is derived from the Greek word hydro, meaning “water former” Carbon is derived from the Latin word carbo, meaning “coal” Calcium is derived from the Latin word calcis, meaning “lime” (as in limestone) Scandium is named for Scandinavia Curium is named for Marie Curie In 1803, English chemist John Dalton (1766-1844) proposed that elements are composed of indivisible, spherical particles – each of these particles are referred to as an atom, from the Greek word atomos, meaning “indivisible” The name of each element is abbreviated using a chemical symbol 14 © 2014 Pearson Education, Inc.

15. Names and Symbols of the Elements Chemical symbols are one or two letters long (capitalize only first letter), and are generally derived from the name of the element Two letters are used if the element starts with the same letter: C is for carbon Co for cobalt (not CO – that is carbon monoxide) Cl for chlorine Some chemical symbols are derived from original Latin or Greek names: Pb for lead, from plumbum Hg for mercury, from hydrargyro Au for gold, from aurum Cu for copper, cuprum Fe for iron, from ferrum 15 © 2014 Pearson Education, Inc. K for potassium, from kalium Na for sodium, natrium Sb for antimony, from stibium Sn for tin, from stannum Ag for silver, argentum

16. Metals, Nonmetals, and Semimetals Three classes of elements: metals, nonmetals, and semimetals A malleable metal can be hammered into a thin sheet of foil A ductile metal can be drawn into a fine wire 16 © 2014 Pearson Education, Inc.

17. Metals, Nonmetals, and Semimetals Metals – high density, high melting point, good conductor of heat and electricity, bright metallic luster, malleable and ductile: aluminum, copper, silver Nonmetals – low density, low melting point, poor conductor of heat and electricity, dull appearance, crush to a powder if hammered: phosphorus, sulfur, carbon Semimetals – midway between metals and nonmetals: silicon, arsenic, boron 17 www.periodictable.com

18. Periodic Table of the Elements Each element is assigned a number, known as the atomic number and elements are arranged by that number in the periodic table 18 © 2014 Pearson Education, Inc.

19. Physical States of the Elements 19 © 2014 Pearson Education, Inc. All metals and semimetals are solid, except for mercury (Hg) 5 nonmetals are solid, 1 is liquid, 11 are gases

20. Compounds and Chemical Formulas Law of definite composition – “compounds always contain the same elements in a constant proportion by mass” Water is always 11.2% hydrogen and 88.8% oxygen, no matter if it is solid, liquid or gas, or where it comes from Sodium chloride is always 39.3% sodium and 60.7% chlorine Most elements occur naturally as a collection of individual atoms A few nonmetal elements, such as hydrogen and oxygen, occur naturally as two or more atoms of the element in a single unit – a molecule 20 © 2014 Pearson Education, Inc. Hydrogen exists as H 2 Oxygen exists as O 2

21. Chemical Formulas In a molecule or compound, a chemical formula expresses the number of atoms of each element present Number of atoms is indicated with a subscript, unless the number is 1 Water contains two hydrogen atoms and one oxygen atom Chemical formula is written as H 2 O Sulfuric acid has two hydrogen atoms, one sulfur atom, and four oxygen atoms Chemical formula is written as H 2 SO 4 21 © 2014 Pearson Education, Inc.

22. Composition of Chemical Formulas State the total number of atoms in a molecule of vitamin B 3 : C 6 H 6 N 2 O There are 15 total atoms: 6 carbon atoms, 6 hydrogen atoms, 2 nitrogen atoms, and 1 oxygen atom Write the chemical formula for vitamin B 6, which is composed of 8 carbon atoms, 11 hydrogen atoms, 1 nitrogen atom, and 3 oxygen atoms C 8 H 11 NO 3 (total 23 atoms) Write the molecular formula for vitamin C, based on the model shown (black = carbon, white = hydrogen, and red = oxygen) 6 carbon atoms, 8 hydrogen atoms, 6 oxygen atoms to give C 6 H 8 O 6 22 © 2014 Pearson Education, Inc.

23. Physical and Chemical Properties The properties of a compound are never the same as its constituent elements – NaCl A physical property refers to characteristics of a pure substance that we can observe without changing the composition of that substance Appearance, melting and boiling points, density, heat, solubility, electrical conductivity, etc. A chemical property of a pure substance describes its chemical reactions with other substances For sodium – its reaction with oxygen to form sodium oxide, and its reaction with water to form hydrogen gas and sodium hydroxide 23 © 2014 Pearson Education, Inc.

24. Physical and Chemical Changes In a physical change, the chemical composition of the sample does not change – ice melts to water (still H 2 O), alcohol vaporizes (still C 2 H 5 OH) In a chemical change, there is a chemical reaction, and a new substance is formed Possible observations: Color change Odor forms Bubbles are seen Gas is released Light energy released Heat energy released 24 © 2014 Pearson Education, Inc.

25. Physical and Chemical Changes 25 © 2014 Pearson Education, Inc. Classify each of the following samples as physical or chemical change a)Touching a lit candle to hydrogen soap bubbles gives an explosion b)Heating water in a flask produces moisture on the glass c)Combining two colorless solutions gives a yellow solid d)Pouring vinegar on baking soda produces gas bubbles e)Freezing water in a freezer makes cubes of ice f)Adding silver nitrate to tap water gives a cloudy solution g)Burning sulfur gives a light blue flame h)Grinding aspirin tablets produces a powder

26. Physical and Chemical Changes 26 © 2014 Pearson Education, Inc. Classify each of the following samples as physical or chemical change a)chemical change b)physical change c)chemical change d)chemical change e)physical change f)chemical change g)chemical change h)physical change

27. Conservation of Mass In the late 1700s, French chemist Antoine Lavoisier found that the mass of reactants before a chemical change was always equal to the mass of products after the change – law of conservation of mass Hydrogen and oxygen always combine in the same ratio by mass to form water 1.0 g hydrogen + 8.0 g oxygen = 9.0 g water Passing an electric current through water produces hydrogen and oxygen 45.0 g water - 5.0 g hydrogen = 40.0 g oxygen The conservation of mass law was used, historically, to determine the formulas of compounds and to develop the first periodic table of elements 27 © 2014 Pearson Education, Inc.

28. Conservation of Mass Law In an experiment, 2.430 g of magnesium metal was ignited and burned with oxygen in the air. If 4.030 g of white magnesium oxide powder, MgO, was collected, what was the mass of oxygen gas that reacted? If 0.654 g of zinc metal reacts with 0.321 of yellow powdered sulfur, what is the mass of the zinc sulfide produced? Heating 1.000 g copper metal with yellow sulfur produces 1.252 g of black copper sulfide. What is the mass of sulfur that reacted with the copper metal? 28 © 2014 Pearson Education, Inc.

29. Conservation of Mass Law In an experiment, 2.430 g of magnesium metal was ignited and burned with oxygen in the air. If 4.030 g of white magnesium oxide powder, MgO, was collected, what was the mass of oxygen gas that reacted? 2.430 g Mg + mass of O = 4.030 g MgO  mass of O = 1.600 g If 0.654 g of zinc metal reacts with 0.321 of yellow powdered sulfur, what is the mass of the zinc sulfide produced? 0.654 g Zn + 0.321 g S = mass of ZnS  mass of ZnS = 0.975 g Heating 1.000 g copper metal with yellow sulfur produces 1.252 g of black copper sulfide. What is the mass of sulfur that reacted with the copper metal? 1.000 g Cu + mass of S = 1.252 g Cu 2 S  mass of S = 0.252 g 29 © 2014 Pearson Education, Inc.

30. Potential and Kinetic Energy Energy is often defined as the ability to do work, there are two types Potential energy (PE) is stored energy that matter posses as a result of its position or composition Kinetic energy (KE) is energy matter has as a result of its motion 30 © 2014 Pearson Education, Inc.

31. Kinetic Energy, Temperature, and Physical State All substances have kinetic energy, regardless of their physical state Solids have the lowest kinetic energy – particles are in fixed positions Liquids – particles possess sufficient energy to have limited movement Gases have the highest kinetic energy – particles are free to fly about As you increase the temperature of a substance, its kinetic energy increases – true for all states of matter Especially important for gases, kinetic energy is directly related to temperature As temperature increases, kinetic energy increases, and motion of particles increases 31 © 2014 Pearson Education, Inc.

32. Kinetic Energy and Molecular Motion A balloon filled with helium (He) gas is cooled from 25 °C to -25 °C. State how each of the following will change: Kinetic energy of the gas Motion of the helium atoms A steel cylinder containing air is heated from 25 °C to 50 °C. State how each of the following will change: Kinetic energy of the gas Motion of the air molecules 32 © 2014 Pearson Education, Inc.

33. Kinetic Energy and Molecular Motion A balloon filled with helium (He) gas is cooled from 25 °C to -25 °C. State how each of the following will change: Kinetic energy of the gas – kinetic energy decreases Motion of the helium atoms – motion decreases A steel cylinder containing air is heated from 25 °C to 50 °C. State how each of the following will change: Kinetic energy of the gas – kinetic energy increases Motion of the air molecules – motion increases 33 © 2014 Pearson Education, Inc.

34. Conservation of Energy Law of conservation of energy – energy cannot be created nor destroyed, but it can be converted from one form to another The conservation of energy law applies to both physical changes and chemical changes There are six forms of energy: Heat – using the burner of a stove top to boil water Light – a lamp brightening a dark room Chemical – burning gasoline Electrical – electric current generated from a battery Mechanical – wind or water spinning a turbine Nuclear – nuclear fusion in the sun 34 © 2014 Pearson Education, Inc.

35. Energy and Physical Changes 35 1 g water + 540 cal 1 g steam Heat energy absorbed 100 °C 1 g steam 1 g water + 540 cal Heat energy released heat energy absorbed (540 cal) = heat energy released (540 cal) When water is converted to steam, heat energy is absorbed by the system (540 cal for 1 g) Energy must be conserved, therefore when steam condenses to water, heat energy is released

36. Energy and Chemical Changes Electrical energy can be used to split water into hydrogen and oxygen (3200 cal for 1 g) When hydrogen and oxygen gas combine to form water, the equivalent amount of heat energy is released 36 © 2014 Pearson Education, Inc.

37. Forms of Energy Each type of energy can be converted from one form to another, and more than one type of energy may come from an object Identify the forms of energy in each conversion: Radioactive emissions vaporize water to steam Steam drives a turbine A turbine spins and drives an electrical generator Identify every form of energy involved in each object: flashlight solar calculator lead-acid battery a star 37 © 2014 Pearson Education, Inc.

38. Forms of Energy Each type of energy can be converted from one form to another, and more than one type of energy may come from an object Identify the forms of energy in each conversion: Radioactive emissions vaporize water to steam  nuclear to heat Steam drives a turbine  heat to mechanical A turbine spins and drives an electrical generator  mechanical to electrical Identify every form of energy involved in each object: flashlight  chemical, electrical, and light solar calculator  light, chemical, and electrical lead-acid battery  chemical and electrical a star  nuclear, light, and heat 38 © 2014 Pearson Education, Inc.

39. Conservation of Mass and Energy In 1905, Albert Einstein presented a paper on the special theory of relativity, that proposed matter and energy are related E = mc 2 E – energy, m – mass, c – speed of light Law of conservation of mass and energy states that the total mass and energy in the universe is constant Decrease in mass corresponds to an increase in energy This is a significant change – a mass loss of 0.001 g produces enough heat energy to raise the temperature of a large swimming pool by 30 °C For ordinary chemical reactions, mass loss is undetectable, but the law is still valid 39 © 2014 Pearson Education, Inc.

40. Summary 40 © 2014 Pearson Education, Inc. Matter exists in three physical states: solid, liquid and gas; changes in temperature leads to changes in physical states Matter can either be a mixture or a pure substance; a mixture can be homogeneous or heterogeneous, and a pure substance can be an element or a compound Elements are composed of indivisible spherical particles called atoms, chemical symbols are used to abbreviate element names An element may be a metal, semimetal, or nonmetal; all elements are ordered by atomic number on the periodic table Law of definite composition – compound always contains the same elements in proportion by mass; chemical formula describes the composition of a molecule Properties of substances are classified as either physical or chemical Changes in substances are also classified as either physical or chemical

41. Summary 41 © 2014 Pearson Education, Inc. Law of conservation of mass states that matter is neither created or destroyed In chemistry, potential energy is related to chemical composition while kinetic energy is related particle motion Law of conservation of energy states that energy is neither created or destroyed; combined law of conservation of mass and energy states that total mass and energy in the universe is constant Key terms: Physical states, sublimation, deposition, heterogeneous mixture, homogeneous mixture, alloys, substance, element, compound, atoms, chemical symbol, metal, nonmetal, malleable, ductile, semimetal, atomic number, periodic table, law of definite composition, chemical formula, molecule, physical property, chemical property, physical change, chemical change, law of conservation of mass, potential energy, kinetic energy, law of conservation of energy, law of conservation of mass and energy