1 / 36

The Nature of Matter

The Nature of Matter . Chapter 2. Atoms. Smallest particle of an element Structure of the atom Nucleus: Protons (+) Neutrons (no charge) Orbital cloud: Electrons (-) Move rapidly can be gained or lost Outer levels have a higher energy. Atoms. Duet rule:

landen
Download Presentation

The Nature of Matter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Nature of Matter Chapter 2

  2. Atoms • Smallest particle of an element • Structure of the atom • Nucleus: • Protons (+) • Neutrons (no charge) • Orbital cloud: • Electrons (-) • Move rapidly can be gained or lost • Outer levels have a higher energy

  3. Atoms • Duet rule: • the closest orbital around the nucleus can hold 2 electrons • Octet rule: • the cloud orbitals can hold up to 8 electrons • This causes attraction between atoms

  4. Atoms • Neon atom • 10 protons • 10 neutron • 10 electrons • Duet Rule • Octet Rule • Stable element

  5. Atoms • Charge of the atom • Sum of protons and electrons • If number of protons = number of electrons  noelectricalcharge

  6. Atoms • Ion: charged particle  lose or gainelectron • Cl- • (gained 1 electron) • Na+ • (lost 1 electron) • Ca2+ • (lost 2 electrons)

  7. Elements • Element • Substance that cannot be chemically broken down further • Consists of entirely one atom

  8. Elements • Mass of the atom • Sum of protons and neutrons • Atomic # • Number of protons

  9. Isotopes • Isotopes • Amount of protons ≠ number of neutrons • Can be more or less • Atomic mass is average masses of element’s isotopes

  10. Isotopes • Radioactive isotopes • Unstable nucleus and break down at a known rate over time • Give off radiation which may be dangerous • Many uses in science • Tracers to follow movement within organisms • Ex: Carbon-14 can be used to detect the age of ancient bones

  11. Chemical Compounds • Compound • Substance that can be broken down to elements (2 or more elements) • 97% of all compounds contain only 6 elements • C-H-O-N-P-S • C-H-O-N = 64%

  12. Chemical Bonds • Atoms in compounds are held together by various types of bonding • Which part of the atom is involved in bond formation? • Bonds form by using valenceelectrons • What types of bonds are there? • Ionic and covalent

  13. Ionic Bond • Ionic bond • Electrons are transferred • Attraction between oppositely charged ions • Ex: Na transfers e- to Cl  Na+Cl- • Become charged particles by gaining or losing electrons

  14. Covalent Bonds • Covalent bond • Pairs of electrons in outer shell shared by both atoms • Can be single (2 electrons) or double (4 electrons)

  15. States of Matter • Solid • Maintains fixed volume and shape • Atoms are more likely linked to each other • Liquid • Maintains a fixed volume • Particles move more frequently • Ability to flow and change into any shape • Gas • Particles move rapidly • Fill volume of container occupied

  16. Chemical Reactions • One or more substances is made or broken down • Reactants • On the left side of an equation • Starting substance(s) • Products • On the right side of an equation • Ending substance(s) CO2 + H2o  H2CO2

  17. Activation Energy • Energy needed in order for a reaction to occur • Substances known as catalysts can lower the activation energy to make a reaction start faster • Living things have catalysts are called enzymes that speed up reactions

  18. Demonstration • Are the pieces of paper without water more attracted to each other? • Why are the pieces of paper with water easier to stick together? • What is holding the papers together? • Water is a polar molecule • Partial negative pole and partial positive side

  19. Polarity An uneven distribution of charges within a molecule In a water molecule the oxygen atom has a greater ability to attract electrons to it, which pulls the hydrogen atoms to one side

  20. Hydrogen bonding Due to partial positive and partial negative poles on the water molecule, other water molecules are attracted to each causing a hydrogen bond Not as strong as covalent or ionic bonding

  21. Hydrogen Bond http://programs.northlandcollege.edu/biology/Biology1111/animations/hydrogenbonds.html What are the other unique properties of water?

  22. Cohesion: The ability for water to be attracted to itself

  23. Cohesion – Surface Tension

  24. Adhesion - The ability for water to be attracted to other substances

  25. Adhesion - Capillary Action What do you think will happen to the daisies? How water moves up plants Plant tubes (xylem) are made of cellulose which is polar Water molecules are attracted to the sides of thin tubes of xylem

  26. Capillary Action How water moves up plants Water molecules are attracted to the sides of thin tubes plant walls This is also why water moves up a straw without you doing anything!

  27. Activity! Drops of water on a penny What properties of water are shown in this experiment?

  28. pH pH is the concentration of hydrogen ions in a solution It is the “potential of Hydrogen”

  29. Strong Acid and Base • HCl – hydrochloric acid • Strong acid • Solution would have a HIGH concentration of H+ ions • H+ loses electron to Cl- • NaOH – sodium hydroxide • Strong base • Solution would have a HIGH concentration of OH- ions • Na+ loses electron to OH-

  30. Buffers Weak acids/bases that react with strong acids or bases to have a gradual shift in the pH scale Ex: Milk calming stomach acid

  31. Why is water neutral? • The molecule of H2O separates into H3O and OH- • H+ loses electron to OH- • Equal parts of each ion • H2O has a neutral pH of 7

  32. pH scale

More Related