1 / 21

Chapter 2, part A

Chapter 2, part A. Chemical Principles. Chemistry. Chemistry is the study of interactions between atoms and molecules. The atom is the smallest unit of matter that enters into chemical reactions. Atoms interact to form molecules. The Study of Atoms. Atoms are composed of

sydnee
Télécharger la présentation

Chapter 2, part A

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. Chapter 2, part A Chemical Principles

  2. Chemistry • Chemistry is the study of interactions between atoms and molecules. • The atom is the smallest unit of matter that enters into chemical reactions. • Atoms interact to form molecules.

  3. The Study of Atoms Atoms are composed of • Electrons: negatively charged particles, no weight • Protons: positively charged particles, 1 amu • Neutrons: uncharged particles, 1 amu • Amu = atomic mass unit 6 X 1023 = 1 gram Atomic weight is the weight of the atom - the sum of it’s parts: protons and neutrons Atomic number is the number of protons.

  4. The Study of Atoms • Protons and neutrons are in the nucleus. • Electrons move around the nucleus. Figure 2.1

  5. Chemical Elements • Each chemical element has a different number of protons - it’s atomic number. • Isotopes of an element are atoms with different numbers of neutrons than typical for that atom. Carbon 14 versus 12. Isotopes of oxygen are: 16 O O O 17 18 8 8 8

  6. Table 2.1

  7. Electronic Configurations • Electrons are arranged in electron shells corresponding to different energy levels.

  8. Electronic Configurations Table 2.2.1

  9. Electronic Configurations Table 2.2.2

  10. How Atoms Form Molecules: Chemical Bonds • Atoms combine to complete the outermost shell. • The number of electrons in this shell is the valence.

  11. How Atoms Form Molecules: Chemical Bonds • A compound contains different kinds of atoms. H2O • The forces holding atoms in a compound are chemical bonds. Types of bonds: • Ionic - exchange of electronics making ions • Covalent - shared electrons • Polar unequal sharing • Hydrogen bonds - between molecules

  12. How Atoms Form Molecules: Chemical Bonds • The number of protons and electrons is equal in a neutral atom. • Ions are atoms that have gained or lost electrons and are charged. Figure 2.2a

  13. Ionic Bonds • Ionic bonds are attractions between ions of opposite charge. One atom loses electrons and another gains electrons. Figure 2.2b

  14. Covalent Bonds • Covalent bonds form when two atoms share one or more pairs of electrons. Figure 2.3a

  15. Hydrogen Bonds • Hydrogen bonds form when a hydrogen atom covalently bonded to an O or N atom in another molecule. Figure 2.4

  16. Molecular Weight and Moles H2O 2H = 2  1 = 2 O = 16 MW = 18 1 mole weighs 18 g • The sum of the atomic weights in a molecule is the molecular weight. • One mole of a substance is its molecular weight in grams.

  17. Chemical Reactions • Chemical reactions involve the making or breaking of bonds between atoms. • A change in chemical energy occurs during a chemical reaction. • Endergonic reactions absorb energy. • Exergonic reactions release energy.

  18. Synthesis Reactions • Occur when atoms, ions, or molecules combine to form new, larger molecules • Anabolism is the synthesis of molecules in a cell. A + B AB  Atom, ion,or molecule A Atom, ion,or molecule B New moleculeAB

  19. Decomposition Reactions • Occur when a molecule is split into smaller molecules, ions, or atoms. • Catabolism is the decomposition reactions in a cell. Breaksdown into AB  A + B New moleculeAB Atom, ion,or molecule A Atom, ion,or molecule B

  20. Exchange Reactions • Are part synthesis and part decomposition. NaOH + HCl NaCl + H2O 

  21. Reversible Reactions • Can readily go in either direction. • Each direction may need special conditions. Heat A + B AB   Water

More Related