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Chapter 2 notes

Chapter 2 notes. Konichek. I. Chemistry-The study of matter and the changes it undergoes A.Pure substance or mixture -Matter with a fixed composition and definite properties 1. elements, and compounds 2. separated using chemical processes.

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Chapter 2 notes

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  1. Chapter 2 notes • Konichek

  2. I. Chemistry-The study of matter and the changes it undergoes • A.Pure substance or mixture-Matter with a fixed composition and definite properties • 1. elements, and compounds • 2. separated using chemical processes

  3. I. Chemistry-The study of matter and the changes it undergoes • A. matter- has mass and occupies space • 1. element- a substance which cannot be broken down any farther by ordinary chemical changes-115 elements- could be more  • a. Atom- This is the smallest piece of an element • 1) 115 or so different types of atoms • 2. element designation • a. one or two letters which are the same world wide

  4. B. compound- two or more elements which are chemically combined • 1. Have different physical properties than the elements which make them up • a. rust- iron(III) oxide, water • 2. Molecule- The smallest unit of a substance that exhibits all the properties characteristics of that substance( Book definition) • a. teacher definition- Two or more elements which are covalently bonded • b. Molecules act as a unit.

  5. C. Chemical formula-Tells the number of elements and atoms in the compound, and the ratio which they combine. • 1. subscript- Tells the number of atoms in the compound • 2. coefficients- tells the number of molecules • H2 + O2-2H2O produces 2 molecules of water

  6. D.Formula mass- this is the sum of the atomic mass of the elements in the compound • E.To find the atomic mass have to look on the periodic table….Oxygen15.999--round it off to 16. • 1.O2= 16 x2= 32 • 2.H2O= 2(1)+ 16= 18 • 3.Be(C2H5O2 )

  7. B. Mixture- Two or more substance which are put together which are not chemically combined • 1. separated using physical means • 2. Types of mixtures • a. heterogeneous-The parts are easily identified • b. Homogeneous- The parts are not easily identified, looks the same throughout • c. Liquid mixtures • 1. miscible- The parts of the mixture don’t separate, and it looks the same throughout • 2. immiscible- Two or more liquids which do not mix with each other. • d. mixing gases with liquids- gases can be dissolved in liquids under pressure.

  8. III. MATTER AND ENERGY( 2.2) • A. Kinetic theory- An explanation of the behavior of matter • 1. All matter is made of atoms and molecules which act as tiny particles • 2. the particles are in constant motion which depends upon the average Ke (temperature)of the substance • a. The particles are constantly colliding without losing energy( perfect elastic collisions) • 3. At the same temperature more massive particles move slower and the less massive move faster • B. KMT - helps understanding the differences in the 3 common states of matter

  9. C, STATES OF MATTER- Depends on the distance and the angles between molecules or atoms • 1. gases- High energy content • a. no definite shape or volume • b. Take the shape of the container

  10. 2. Helium filled balloons lose air faster than air filled balloon- because the small He atom can go through the membrane of the balloon easier. • 3. pressure- the gases colliding with the sides of the container, as more atoms go inside the balloon the more collisions occur... eventually the balloon will burst

  11. 2. Liquids- Have a definite volume, but no definite shape • a. The atoms are able to move about each other freely • 1. fluids- all liquids and gases • b. Viscosity-A fluids ability to flow • 1. Depends upon an attraction between particles in the liquid

  12. 3. Solids- Have definite shape and volume • a. The atoms are in a definite arrangement, this provides the shape • b. relatively low energy content. • c. Strong attraction between atoms or molecules

  13. D ENERGIES ROLE • 1. MELTING- THE PROCESS OF CHANGING A SOLID TO A LIQUID • a. The particles are changing their positions and gaining energy, so they will not want to remain in their set positions. • 2. Evaporating- The particles have gained enough energy to escape from the liquid form to the gaseous form

  14. 3. CONDENSATION- The process of changing from a gas to a liquid- losing heat. • 4. Sublimation- When a substance goes from a solid directly into a gas • a, dry ice, iodine • 5. During a change in state composition remains constant and no mass is lost • E. Conservation of mass- Mass cannot be created or destroyed. • 1. Must end up with the same amount of matter which is started with

  15. F. conservation of energy- Energy cannot be created or destroyed- First Law of Thermaldynamics • a. The total amount of energy during a chemical reaction remains constant • 1. Burning of gasoline in a car engine

  16. IV. PROPERTIES OF MATTER • A. Chemical and physical properties • 1. Chemical property- the way a substance reacts with other substances to form new substances with different physical properties. • 1. H2 + O 2----> H2O • 2. Reactivity- The ability of a substance to combine chemically with other substances. • a. depends upon their position on the periodic table.

  17. 2. physical property-a characteristic of a substance which can be observed or measured without changing the composition of the substance. • a, color, size, shape, state, density. melting point, boiling point. • b. density- mass per unit volume- characteristic property • 1. D= mass/ volume d=m/v • 2, buoyancy- The force with which more dense fluid pushes a less dense substance upward.

  18. V. CHEMICAL AND PHYSICAL CHANGES • A. Chemical changes- A change that occurs when a substance changes composition by forming one or more new substances. • 1. Have different physical properties • 2. electrolysis of water. • 3. burning of gasoline- Changes the composition • B. physical changes- the composition doesn’t change.

  19. Physical change- a change in state

  20. Chemical change- rusting of a nail

  21. 1. The atoms which make up don’t change or are rearranged • 2. A change in size, shape, or state. • 3. Dissolving is a physical change- sugar in water

  22. SUMMERIZING • 1.Definition Physical ChangeThe matter is the same.2.The original matter can be recovered.The particles of the substance are rearranged. • 3.Chemical ChangeThe matter is different. The old matter is no longer present. • 4.The original matter cannot be recovered. • 5.The particles of the substance are broken apart, and the atoms are rearranged into new particles, forming a new substance.

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