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Basic Chemistry

Learn about matter, energy, atomic structure, chemical bonds, and more in this beginner's guide to basic chemistry concepts.

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Basic Chemistry

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  1. Basic Chemistry

  2. Matter and Energy • Matter—anything that occupies space and has mass (weight) • Energy—the ability to do work • Chemical • Electrical • Mechanical • Radiant

  3. Composition of Matter • Elements—fundamental units of matter • 96% of the body is made from four elements • Carbon (C) • Oxygen (O) • Hydrogen (H) • Nitrogen (N) • Atoms—building blocks of elements

  4. Atomic Structure • Nucleus • Protons (p+) • Neutrons (n0) • Outside of nucleus • Electrons (e-) Figure 2.1

  5. Atomic Structure of Smallest Atoms

  6. Identifying Elements • Atomic number—equal to the number of protons that the atom contains • Atomic mass number—sum of the protons and neutrons

  7. Isotopes and Atomic Weight • Isotopes • Have the same number of protons • Vary in number of neutrons Figure 2.3

  8. Isotopes and Atomic Weight • Atomic weight • Close to mass number of most abundant isotope • Atomic weight reflects natural isotope variation

  9. Radioactivity • Radioisotope • Heavy isotope • Tends to be unstable • Decomposes to more stable isotope • Radioactivity—process of spontaneous atomic decay

  10. Molecules and Compounds • Molecule—two or more like atoms combined chemically • Compound—two or more different atoms combined chemically

  11. Chemical Reactions • Atoms are united by chemical bonds • Atoms dissociate from other atoms when chemical bonds are broken

  12. Electrons and Bonding • Electrons occupy energy levels called electron shells • Electrons closest to the nucleus are most strongly attracted • Each shell has distinct properties • The number of electrons has an upper limit • Shells closest to the nucleus fill first

  13. Electrons and Bonding • Bonding involves interactions between electrons in the outer shell (valence shell) • Full valence shells do not form bonds

  14. Inert Elements • Atoms are stable (inert) when the outermost shell is complete • How to fill the atom’s shells • Shell 1 can hold a maximum of 2 electrons • Shell 2 can hold a maximum of 8 electrons • Shell 3 can hold a maximum of 18 electrons

  15. Inert Elements • Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state • Rule of eights • Atoms are considered stable when their outermost orbital has 8 electrons • The exception to this rule of eights is Shell 1, which can only hold 2 electrons

  16. Inert Elements Figure 2.5a

  17. Reactive Elements • Valence shells are not full and are unstable • Tend to gain, lose, or share electrons • Allow for bond formation, which produces stable valence

  18. Chemical Bonds • Ionic bonds • Form when electrons are completely transferred from one atom to another • Ions • Charged particles • Anions are negative • Cations are positive • Either donate or accept electrons

  19. Ionic Bonds + – Cl Na Cl Na Sodium atom (Na)(11p+; 12n0; 11e–) Chlorine atom (Cl)(17p+; 18n0; 17e–) Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride (NaCl) Figure 2.6

  20. Chemical Bonds • Covalent bonds • Atoms become stable through shared electrons • Single covalent bonds share one pair of electrons • Double covalent bonds share two pairs of electrons

  21. Examples of Covalent Bonds Figure 2.7a

  22. Examples of Covalent Bonds Figure 2.7b

  23. Examples of Covalent Bonds Figure 2.7c

  24. Polarity • Covalently bonded molecules • Some are non-polar • Electrically neutral as a molecule • Some are polar • Have a positive and negative side Figure 2.8

  25. Chemical Bonds • Hydrogen bonds • Weak chemical bonds • Hydrogen is attracted to the negative portion of polar molecule • Provides attraction between molecules

  26. Hydrogen Bonds Figure 2.9

  27. Patterns of Chemical Reactions • Synthesis reaction (A + BAB) • Atoms or molecules combine • Energy is absorbed for bond formation • Decomposition reaction (ABA + B) • Molecule is broken down • Chemical energy is released

  28. Synthesis and Decomposition Reactions Figure 2.10a

  29. Synthesis and Decomposition Reactions Figure 2.10b

  30. Patterns of Chemical Reactions • Exchange reaction (AB + CAC + B) • Involves both synthesis and decomposition reactions • Switch is made between molecule parts and different molecules are made

  31. Patterns of Chemical Reactions Figure 2.10c

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