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Chapter 18

Chapter 18. Matter. Section 1 Atoms. A. Matte r—anything that has mass and takes up space 1. Matter is made up of tiny particles called atom s. 2. Substances that contain only one type of atom are element s. 3. Elements are found in the Periodic Table.

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Chapter 18

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  1. Chapter 18 Matter

  2. Section 1 Atoms • A. Matter—anything that has mass and takes up space • 1. Matter is made up of tiny particles called atoms. • 2. Substances that contain only one type of atom are elements. • 3. Elements are found in the Periodic Table

  3. B. Three basic particles make up an atom: protons,neutrons, and electrons. • 1. Protons and neutrons make up the nucleus of an atom. • a. Protons—particles that have a positive electric charge • b. Neutrons—particles that have no electrical charge • - The nucleus has a positive charge.

  4. 2. Electrons—negatively charged particles that move around the nucleus • a.Electrons are found in energy levels around the nucleus • b.First energy level can hold 2 electrons • c.Second energy level can hold a maximum of 8 electrons

  5. d.Third energy level can hold 18 electrons • e.Fourth energy level can hold 32 electron • f.N(squared) x 2 = #of electrons in the energy level (N is the energy level) • g.Draw the model for Carbon, Nitrogen, Chlorine and Sodium • Show the nucleus and electron cloud

  6. 3. Atomic number—the number of protons in an atom’s nucleus • a. All atoms of a specific element have the same atomic number. • b. This number also equals the number of electrons in the atom’s electron cloud.

  7. 4. Mass number—the number of protons and neutrons making up an atom’s nucleus

  8. 5. Using the periodic Table find the number of electrons, protons and neutrons for • a.Na • b.Mg • c.I • d.Cl • e.Au • f.Fe

  9. C. Isotopes—atoms of the same element that have different numbers of neutrons

  10. Discussion Question • It was once thought that the atom was the smallest particle possible. Why is that no longer believed?   • We now know that atoms are made up of even smaller particles: protons, neutrons, and electrons.

  11. Section 2 Combinations of Atoms

  12. A. When atoms of more than one element combine, they form a compound. • B. Chemical property—describes a change that occurs when one substance reacts with another substance

  13. C. Bond—the force that holds atoms in compounds together • - Compound form to become stable • - Atoms are stable when their outer energy level is full or when they have eight electron in their outer energy level • - There are two type of bonds that make compounds

  14. These are the Noble Gases and have very stable electron arrangements eg 2, 2.8 and 2.8.8 because their outer shells are full. The first three are shown in the diagrams below and explains why Noble Gases are so reluctant to form compounds with other elements.

  15. 1.Covalent bonds form by sharing electrons. 2. Atoms that combine if they become positively or negatively charged have ionic bonds. • a.They become positive or negative by gaining or losing electrons • b.Electrically charged atoms are called ions. c. Ions are attracted to each other when they have opposite charges.

  16. Other types of bonds • 3. Metallic bonds—electrons are free to move from one ion to the other. • a. Found in metals such as copper, gold, aluminum, and silver • b. Give metals the ability to conduct electricity

  17. 4. Hydrogen bonds—form when the positive end of one molecule is attracted to the negative end of another molecule • a. Form without the interaction of electrons • b. Responsible for the property of cohesion—allows water to form raindrops • c. Hydrogen bonds are easily broken.

  18. Water strider not heavy enough to break hydrogen bonds

  19. Cohesion

  20. Cohesion and hydroplaning

  21. Mixture and solutions

  22. D. Mixture—two or more substances that are not chemically combined • 1. Heterogeneous mixture—components not mixed evenly; each component retains its own properties. • 2. Homogenous mixture—compounds evenly mixed; can’t see each component; also called solutions

  23. Vinegar and oil-heterogeneous

  24. Sugar water- Solution

  25. Homogeneous – Rubbing alcohol isopropanol + water

  26. 3.The components of a mixture can be separated by physical means. • a.Ex. Marbles from wood chips • 4. The components of a compound must be separated by chemical means. To break down compounds, several steps are required

  27. Discussion Question • Why are materials with metallic bonds malleable, or easily shaped? • Their electrons are free to move from one ion to the other.

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