Presentation on theme: "“STUFF” Matter and Energy. What is Matter? Matter is anything that has both mass and volume. Mass is a measurement of the amount of “stuff” in an object."— Presentation transcript:
What is Matter? Matter is anything that has both mass and volume. Mass is a measurement of the amount of “stuff” in an object. Volume is a measurement of the quantity of space that an object occupies. Note: Weight is not the same thing as mass. Weight is the force of gravity on an object.
What is Matter Made of? All matter is made up of atoms. An atom is the smallest unit of an element that has the properties of that element. All of the known elements can be found on the Periodic Table. Atoms are combined in various ways to make up all of the different kinds of matter.
Physical Properties A physical property of a substance is a characteristic that can be observed or measured without changing the chemical makeup of a substance. Physical properties include: colorodor densityviscosity hardnessmalleability melting pointelectrical conductivity boiling pointslipperiness
Extensive vs. Intensive Properties Depend on amount of substance present mass length volume Independent of amount of substance density boiling point melting point
Chemical Properties A chemical property is a characteristic of matter that describes the ability of a substance to change (or not change) composition when in contact with other substances. Examples of chemical properties include: burns in airis toxic explodesdecomposes when heated reacts with certain acids reacts with certain metals
Physical Changes A physical change is a change in a substance that does not involve a change in the identity of the substance. grinding, cutting, melting, and boiling A change of state is a physical change of a substance from one state to another.
States of Matter Solid – definite shape and volume Liquid – constant volume but shapes changes with the container Gas – takes shape of container and fills the entire volume of the container Plasma – ionized, highly reactive gas
Chemical Changes A change in which one or more substances are converted into different substances is called a chemical change or chemical reaction. The key difference between a physical and chemical change is that a chemical change always produces a new substance. In a physical change, the substance does not change into something else.
Describing a Chemical Reaction Indications of a Chemical Reaction Evolution of heat, light, and/or sound Evolution of heat, light, and/or sound Production of a gas Production of a gas Formation of a precipitate Formation of a precipitate Color change Color change
Signs of Chemical Reactions There are five main signs that indicate a chemical reaction has taken place: change in colorchange in odorproduction of new gases or vapor input or release of energy release input formation of precipitate
Chemical Reactions The starting substances turn into different substances by rearranging the atoms. Mass is conserved in chemical reactions. Starting substances = reactants Ending substances = products
Energy Energy is always involved when physical or chemical changes occur. Energy can be in various forms. heat light Energy can be absorbed or released in a change, it is not destroyed or created. (This is called the law of conservation of energy.)
Temperature Temperature is a measure of the average kinetic energy of the particles in a sample of matter. (This is related to how fast the particles are moving. If two particles are identical, the one moving faster has more kinetic energy.) The greater the kinetic energy of the particles in a sample, the hotter it feels. Example: the particles in liquid water move faster than the particles in ice. For calculations in chemistry, the Celsius and Kelvin temperature scales are used.
Heat Heat can be thought of as the energy transferred between samples of matter because of a difference in their temperatures. Energy transferred as heat always moves a higher temperature to a lower temperature. Image from OpenStax College Physics
Energy in Chemical Reactions A chemical reaction that releases energy is exothermic, and the energy of the products is less than the energy of the reactants. The products in an exothermic reaction will feel warmer than the reactants. In an endothermic reaction, the products have a higher energy than the reactants, and the reaction absorbs energy. The products in an endothermic reaction will feel colder than the reactants.
Pure Substances A pure substance contains only one kind of particle. A pure substance has a set of definite physical and chemical properties. Types of pure substances: An element has only one kind of atom. A compound is made by combining atoms of 2 or more different elements. Compounds can be broken down into elements.
Pure Substances Element composed of identical atoms EX: copper wire, aluminum foil Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Pure Substances Compound composed of 2 or more elements in a fixed ratio properties differ from those of individual elements EX: table salt (NaCl) Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Mixtures A mixture is the combination of two or more substances that remain chemically separate. A homogeneous mixture is a combination that is uniform in composition and appearance. A heterogeneous mixture is uneven in composition and appearance. A heterogeneous mixture can usually be visibly identified as a mixture.
Mixtures Variable combination of 2 or more pure substances. HeterogeneousHomogeneous Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Mixtures HeterogeneousHomogeneous does not blend smoothly multiple substances can be seen has a uniform composition also called a solutio n
Mixtures Solution o homogeneous o very small particles o no Tyndall effect o particles don’t settle o EX: rubbing alcohol o Tyndall effect = light is scattered as it passes through (appears cloudy) Tyndall Effect Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Mixtures Examples: mayonnaise muddy water fog saltwater Italian salad dressing colloid suspension colloid solution suspension Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes ColloidsSuspensions Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem