6:50 am

Chapter 4 Physics

• "... many scientists have been campaigning for a flip in the educational sequence, teaching physics first, the life sciences last. ... argue that physics is the foundation on which chemistry and biology are built." [p. 88]
  
  
• "Everything, every single thing deserving of the designation 'thing', is made of atoms." [p. 89]
  
  
• "If we could blow up an atom to something the size of a paperweight, 'what would we see'? ... It depends on your definition of see. ... When we talk about seeing things in the everyday world, we're talking about ... photons of light. ... But when you get down to the scale of the atom, those photons change the nature of the thing you are seeing. ... We can't literally see down there." [p. 90]
  
  
• "The atoms remain discrete entities, distinct particles composed of protons and neutrons in the nucleus, a huge amount of hollow space, and a cloud cover of electrons located far, far away from the nucleus." [p. 91]

• The identity of an atom is determined by the number of protons in the nucleus. Usually an atom has the same number of neutrons as protons in the nucleus, although some atoms have quite a few more neutrons than protons. In addition to the "normal" complement of protons and neutrons, some atoms may have one or two more or less neutrons than the regular atoms for that element. Such atoms are called isotopes of that element. An atom also "normally" has the same number of electrons as protons and is thus electrically neutral. If an atom has a couple of electrons more (or less) than the number of protons, then it is called an ion of that element.
  
  
• "The terms positive and negative are [arbitrary]. ... The vocabulary could as easily been reversed, and the proton designated as negatively charged and the electron pronounced positive, but they weren't. ... What is important is that the charge of one counterbalances the charge of the other." [p. 93]
  
  
• "A particle's charge is not a measure of the particle's energy content. ... A particle is deemed charged by its capacity to attract or repel other charged particles. 'A charge is an attitude; it is not in itself anything.' " [p. 94]
  
  
• There are 4 fundamental forces: electromagnetism, gravity, strong and weak. "A fundamental force is best thought of as a fundamental interaction, a relationship between tow chunks of matter. It turns out that there are just four known ways that one piece of matter can communicate with another ... Each of these interactions differs in strength and range, operates according to a distinct set of rules, and yields distinct results." [p. 94]
  
  
• "Physicists propose that the four forces are really four manifestations of a single undrlying superforce, and that when our universe was young, firm, and hot, the forces behaved as one too; only with the inevitable aging and cooling and spreading of the cosmos did the single force fracture into four separate instruments. Scientists' quest to unite the four forces into a single equation, a Grand Unifying Theory, ... is an effort to discover the primal commonality underlying the current plurality." [p. 95]
  
  
• "Electrons cannot flit about wherever they please, but are confined to specific zones, or shells, around the protons to which they are so attracted. The shells are arrayed one inside the other, and each is able to accommodate a set number of electrons." [p.96]
  
  
• "Sometimes, if an atom is blasted with a beam of light, a few of its electrons may become stimulaated and jump to vacancies in shells farther from the nucleus. But 'jump' ... does not mean 'bound in a continuous motion from here to there'; it means 'disappear momentarily from the shell I was in and reappear suddenly in the shell above me'." This is called a "quantum leap". [p. 97]
  
  
• The reason that everything appears solid is that the electron clouds of two different atoms strongly repel one another. [p. 98]
  
  
• "As far as we know, electrons are elementary particles, meaning they can't be broken down into even smaller particles. Scientists can crack apart the nuclear particles, the protons and neutrons, into even smaller particles, called quarks." [p. 99]
  
  
• "Charged atoms seek to fill their vacant shells or to shed their excess electrons. ... when metal atoms arrange themselves into molecules, the electrons in their outer shells are often loosely attached and free to roam about from one metal atom to another. The neighbourly sharing of electrons tends to strengthen the bonds among atoms, lending metals their legendary toughness." [p. 100]
  
  
• "How are electricity and magnetism related? ... They both generate fields of their own - magnetic fields and electric fields - and the field of one force can affect the behavior of the other force. To talk about a 'field' is another way of saying, action at a distance." [p. 107]

8:20 am

Chapter 5 Chemistry

• "We're just self-replicating carbon units, that's what we are. ... We're not a heck of a lot different than the carbon-based fiber in a steel-belted radial tire, so maybe we shouldn't take ourselves too seriously." [p. 121]
  
  
• "On earth, under our conditions, we have lots of chemistry. We have temperature conditions where molecules can exist in three different states, as solid, liquid, or gas, and where, with the input of energy, from the light of the sun or the heat of a fire, those molecules can change into other molecules, into other complex assemblages of atoms." [p. 123]
  
  
• "There are at least 100,000 different molecules in the human body." [p. 123]
  
  
• "To merit designation as molecules or chemical compounds, the constituent atoms must be stuck together with some sort of electromagnetic glue. The atoms must share their outermost electrons with one another, or must feel the persistent tugging of an oppositely charged atom by their side." [p. 124]
  
  
• "Chemistry is about molecules, and making and breaking bonds." [p. 124]
  
  
• "Beyond studying the world as it exists, we can put together combinations of molecules in ways never dreamed of before." [p. 124]
  
  
• "My field is materials chemistry, an one thing we don't admit to young students is how clueless we really are. ... Much of what we come up with we happen on by trial and error, and we can't predict what we'll get ahead of time." [p. 124]
  
  
• "The strongest and simplest ... bond in nature is the covalent bond, where tow atoms team up and share a pair or more of electrons. ... The outermost shells don't really need extra electrons ... the number of orbiting, negatively-charged electrons balancing the number of positively charged protons within ...but atoms with a moderate degree of empty shell space often ... swap their outermost electrons back and forth." [p. 125]
  
  
• "An ionic bond is a bond between ions, or electrically charged atoms." [p. 128]
  
  
• "... a metallic bond is ... one where the outermost electrons float about in what's often called an 'electron sea', being tugged first toward one atom, then toward another, their fluidity accounting for a metal's capacity to conduct an electric current." [p. 130]
  
  
• " ... a hydrogen bond is ... like a Mickey Mouse head. ... [Consider water] It turns out that the electron pairs binding each hydrogen ear and the oxygen skull are not quite fairly, squarely, and roundly shared. They tend to spend a bit more time near the oxygen nucleus than near the proton core of either hydrogen atom. As a result, the ears of Mickey molecule have a slight positive charge: their protons are not always fully counterbalanced by a constant cloud of negative charge. At the same time , because the oxygen atom is hogging a bit too much of the shared electrons' attentions, the bottom half ... has a modest negative charge. The molecule is polarized ... The chins of one molecule are drawn gently toward the ears of another, lending water ... its exceptional clinginess. ... Hydrogen bonds are only about one-tenth as strong as covalent bonds, but what they lack in strength they make up for with elasticity." [p. 130 - 131]
  
  
• "Another intermolecular melder is the van der Waals force. ... the weakest of the links ... similar in nature to a van der Waals force ... examples include clay and graphite." [p. 132]
  
  
• About 60% of our body weight is water. Of the remainder about 2/3 is composed of carbon atoms. [p. 133]
  
  
• "Carbon makes for a just right class of molecules. ... With its outer shell of four electrons and four electron slots empty, it is supremely suited to molecular bonding. ... Moreover, carbon is unparalled among elements in its ability to join with itself almost indefinitely, forming carbon chains and carbon loops and branching carbon prongs and ... Moreover again, the bond between two carbon atoms is one of the strongest bonds known." [p. 134]