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Matter & Energy

This comprehensive guide delves into the fundamental concepts of matter and energy, discussing their properties, interactions, and the underlying principles that govern the natural world. Matter is defined as anything with mass and volume, with atoms as the fundamental units. Energy is explored as the driving force behind all changes, governed by the principle of conservation. The relationship between mass and energy is highlighted by Einstein's famous equation E=mc². Key topics also include atomic structure, isotopes, and the formation of bonds, providing insights into chemistry's foundational elements.

malcolm-kirby
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Matter & Energy

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  1. Matter & Energy Foundations of the Natural World

  2. Matter • If it exists, it’s matter • You, a rock, oxygen… • has mass; takes up space (volume) • Fundamental unit: the atom • Atoms vary by # of protons • each a different element • Organized into the periodic table • Can be changed, yet is always conserved

  3. Energy • Makes things happen • Do work • Reorganize matter • Comes in different forms • in the chemical bonds of the food we eat • radiant energy from the sun • Can be changed, yet is always conserved

  4. Mass is energy? • In the early 20th century, scientists hypothesized that mass and energy are linked. • Albert Einstein provided the mathematical evidence with his famous equation, E = mc2 • "E" ="energy," • "m" denotes "mass" • "c" is the speed of light

  5. New Boys Atomic structure Pro’s Elected ones the ‘hood WKRP atomic structure.webloc

  6. Atomic structure neutron atomic nucleus Proton: + charge Electron: - charge

  7. Sub-atomic structure Some sub-atomic particles have sub-particles themselves! Up quark charge +2/3 Down quark charge -1/3 Do the math! p = 2 ups, 1 down n = 1 up, 2 down e- ? Its a fundamental particle

  8. Unstable nuclei Potential problem in nucleus : like charges (++) repel Neutrons break up charge; if they can’t, particles are ejected • changes the number of protons • changes the element • a radioactive atom (more in C/D IS year)

  9. Electrons orbit the nucleus Orbit model vs Orbital model • Negative electrons orbit the positive nucleus The first - nearest the nucleus - can hold up to 2 e- The others hold 8e- or more , but are ‘full’ once they have 8

  10. Element info element atomic number = protons infer electrons If p <> e, then an ion symbol atomic mass = nuclear mass # protons + neutrons why .003? Isotopes!

  11. Isotopes vary in # of neutrons Isotopes of H 1 a.m.u.* 2 a.m.u. 3 a.m.u. *a.m.u. = 1 atomic mass unit number of nuclear particles = mass number

  12. Electron dot model* – shows valence e- The number of e- in the outermost orbitDetermines if the atom will form bonds 12 e- 2•18•2 valence e- 10 e- 2•8•8 valence e- 6 e- 2•8•4 valence e- *aka Lewis dot

  13. Oxidation Number determinedby valence e- Determines which atoms are likely to bond with which other atoms is the outer orbit more empty, or more full? 2 valence e- • donates 2 • +2 oxidation # 6 valence e • accepts 2 • -2 oxidation # It’s a match!

  14. Periodic patterns Groups - Same valence/oxidation # Periods - Same # shells/orbits No stable isotopes synthetic the element song

  15. Periodic patterns Periods - Same # shells/orbits No stable isotopes synthetic the element song

  16. 11 p+ 17 p+ 11 e- 17 e- Ionic bonds Valence stability achieved by moving an electron to another atom Creates charge imbalance Atoms become ions Positive & negative ions attracted to one another Oppositely charged ions form an ionic bond - + 11p+ 17P+ 10 e- 18 e-

  17. Another view Oxidation: +1 -1 p+ to e- ratio: 11:10 17:18

  18. Covalent bonds Atoms have an equal attraction to the electrons Share electrons Electrons orbit both atoms equally

  19. Polar covalent bonds + Electrons more attracted to one atom type – reflects electronegativity Share e- unequally - + Result? Regions of molecule are weakly positive and negative

  20. Ionic Bonds metal with non- metal very different valences electrons donated/accepted ex: NaCl 1 7 Na Cl go either way

  21. Covalent Bonds Non-metal with non-metal similar valences electrons shared ex: CO2 4 6 C O go either way

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