Matter and Energy Zumdahl Chapter 3
Grand Prismatic Spring in Yellowstone National Park Source:David Maisel/Stone/Getty Images
Universe Classified • Matter is the part of the universe that has mass and volume • Energy is the part of the universe that has the ability to do work • Chemistry is the study of matter • The properties of different types of matter • The way matter behaves when influenced by other matter and/or energy
3.1 Matter AIMS -learn about matter and its three states
Matter • What is Matter??? • Anything that has mass and occupies a volume • “Matter is the real substance of which actual physical objects - the 'things' of this world - are composed.” Sir Roger Penrose. • Can also be thought of as being composed of protons, neutrons, and electrons (more on that later)
All Matter exists in one of 4 Physical States • Gaseous-no definite shape or volume • Liquid-definite volume, but not shape • Solid-definite shape and volume • Plasma-like gases, but atoms are made up of free electrons and ions of the element.
Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior gas liquid solid assumes the shape and volume of its container particles can move past one another assumes the shape of the part of the container which it occupies particles can move/slide past one another retains a fixed volume and shape rigid - particles locked into place compressible lots of free space between particles not easily compressible little free space between particles not easily compressible little free space between particles flows easily particles can move past one another flows easily particles can move/slide past one another does not flow easily rigid - particles cannot move/slide past one another
Solid Liquid Gas Ice cube, diamond, iron bar, rock Gasoline, water, alcohol, blood Air, helium, oxygen, natural gas Examples of substances and their commonly found state
What determines the Physical State of a particular substance? • Temperature • Melting point or boiling point of substance
What causes a substance to change into another Physical State? • Addition of energy -melting -boiling • Subtraction of Energy -freezing -condensing (condensation)
Densities of Physical States • Gases • Least dense • Occupy about 16oo greater volume than liquids • Liquids • Density similar to solids, little less • Solids • Most dense of states
This photo shows a 2.5 kg Brick being supported by only 2 grams of aerogel
Mercury, on the other hand, is a very dense liquid, denser than some solids
3.2 Physical and Chemical Properties and Changes AIMS learn to distinguish between physical and chemical properties -learn to distinguish between physical and chemical changes
Properties • Characteristics of the substance under observation • Properties can be either • directly observable or • the manner something interacts with other substances in the universe
Properties of Matter • Physical Properties are the characteristics of matter that can be observed without changing its composition • Characteristics that are directly observable • Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy • Characteristics that describe the behavior of matter
What is a Physical Property? • A physical property is a characteristic of a substance that does not change as you determine that property. Example: In order to determine that a domino is black, all you do is look at it. The domino remains unchanged during the test Example: In order to determine if a rock contains the mineral magnetite, you could place a paperclip nearby and see if it sticks. The rock remains unchanged during this test.
Examples of Physical Properties • Odor • Color • Physical state • Boiling/melting point • Density • Magnetic/not • Hardness • Radioactivity • Malleability • Ductility
Gallium metal has such a low melting point (30°C) that it melts from the heat of a hand.
An iron pyrite crystal (gold color) on a white quartz crystal. Source: Chip Clark
What is a Chemical Property? • A chemical property is a characteristic of a substance which, when determining, will change an example would be …when determining the flammability of a substance, we must burn it, and thereby change it. chemical properties refer to the ability of a substance to form new substances
Some Chemical Properties • Flammability -is the material flammable? • Reactivity • -does material react with another chemical, in what way? • pH • What is the pH of the substance?
Classify Each of the following as Physical or Chemical Properties • The boiling point of ethyl alcohol is 78°C. • Physical property – describes inherent characteristic of alcohol – boiling point • Diamond is very hard. • Physical property – describes inherent characteristic of diamond – hardness • Sugar ferments to form ethyl alcohol. • Chemical property – describes behavior of sugar – forming a new substance (ethyl alcohol)
Changes in Matter • Physical Changes are changes to matter that do not result in a change the fundamental components that make that substance • State Changes – boiling, melting, condensing • Chemical Changes involve a change in the fundamental components of the substance • Produce a new substance • Chemical reaction • Reactants Products
What is a Physical change? • Any change that does not change the chemical makeup of a substance • Examples include: • Changes in physical state • Crushing, grinding, tearing
What is a Chemical change? • Any change that results in materials with a different chemical nature. • Examples: • Electrolysis • Burning (combustion) • Silver tarnishing
Figure 3.3: Electrolysis, the decomposition of water by an electric current, is a chemical process. Electrolysis Link
Signs of a Chemical Change • Color Change • Formation of a gas (not from a phase change) • Energy absorbed or given off • Gets cold or hot • Gives off light/electric charge/other energy • Formation of a precipitate
Oxygen combines with the chemicals in wood to produce flames. Is a physical or chemical change taking place? Source: Jim Pickerell/ Stone/Getty Images
Classify Each of the following as Physical or Chemical Changes • Iron metal is melted. • Iron combines with oxygen to form rust. • Sugar ferments to form ethyl alcohol.
Classify Each of the following as Physical or Chemical Changes • Iron is melted. • Physical change – describes a state change, but the material is still iron • Iron combines with oxygen to form rust.. • Chemical change – describes how iron and oxygen react to make a new substance, rust • Sugar ferments to form ethyl alcohol. • Chemical change – describes how sugar forms a new substance (ethyl alcohol)
Classification of Matter • Homogeneous = uniform throughout, appears to be one thing • pure substances • solutions (homogeneous mixtures) • Heterogeneous = non-uniform, contains regions with different properties than other regions
3.3 Elements and Compounds AIM: to understand the definitions of elements and compounds
Elements • Cannot be separated into simpler substances • Fundamental form of matter • Examples include iron, oxygen, aluminum, and hydrogen • There are 90 naturally occurring elements, about 118 known elements
Compounds • Have same composition no matter where they are found • ALWAYS made up of atoms of 2 or more elements, chemically combined • Can be broken into the constituent elements by chemical changes
Elements and Compounds • Substances which can not be broken down into simpler substances by chemical reactions are called elements • Most substances are chemical combinations of elements. These are called compounds. • Compounds are made of elements • Compounds can be broken down into elements • Properties of the compound not related to the properties of the elements that compose it • Same chemical composition at all times
A Model of an oxygen molecule…. Is this an element or a compound?
Element Element Compound
Would you put elemental sodium metal and chlorine gas on your popcorn????? Or would you put a compound composed of sodium ion and chloride ion (NaCl) on it?
Pure Substances vs. Mixtures • Pure Substances • All samples have a unique set of physical and chemical properties • Constant Composition all samples have the same composition • Homogeneous (meaning same throughout) • Separate into components based on chemical properties • IncludeElements and Compounds • Mixtures • Different samples may show different properties • Variable composition • Homogeneous or Heterogeneous (different throughout) • Separate into components based on physical properties • All mixtures are made of pure substances