Unit 1: Chemistry of Life Flashcards
What is the metric system conversion stairs? How do you convert between them?
Remember: King Henry Died Unexpectedly Drinking Chocolate Milk
1. Kilo-1000
2. Hecto-100
3. Deca- 10
4. Meter/Liter/Gram- 1
5. Deci- 0.1
6. Centi- 0.01
7 Milli- 0.001
To convert between them:
As you go up the steps, (milli to kilo), you divide by 10. As you go down the steps (kilo to milli), you multiply by 10.
Convert 10 mm to km.
10mm = 0.00001km
What are the four factors of significant figures?
N- Non-zero numbers are always significant.
E- Embedded zeros are always significant.
Ex. 2003- 4 significant figs
L- Leading zeros are never significant.
Ex. 0.001- One significant fig
T-Trailing zeros are significant only if they contain a decimal place.
Ex. 2.30- 3 significant figs
200- One significant fig
Calculate the significant figure of the following calculation.
3.54 x 2.6458 x 7.48764
Full answer should be 70.130224 but final answer according to significant figures should be 70.1
Calculate the significant figure of the following calculation.
38.65 x 105.93
Reduce to 4 sig figs 4,094
Calculate the significant figure of the following calculation.
22.903m x 0.0092m x 16.9753m =
3.6m^3
What is a fact?
A fact is an observation so firmly supported by evidence that we assume it’s true, and act as if it were true. (There is no certainty in science).
What is a hypothesis?
A casual explanation of an observation/fact that has not been sufficiently tested.
What is a scientific theory?
A well-substantiated explanation of some aspect of the natural world, based on a body of facts and laws that have been repeatedly confirmed through observation and experiement.
What is scientific law?
Describes a natural phenomenon
What is the valence shell?
The outermost shell of an atom with e^- is called the valence shell.
What is valence?
The number of unpaired electrons in the outermost shell is called its valence.
When are atoms the most stable? Give an example.
Atoms are most stable when the valence shell is full.
Ex. Hydrogen atoms each have one unpaired electron in their electron shells. An H2 molecule has two shared electrons through a covalent bond
What are the four factors of a covalent bond?
S- Protons and neutrons are shared by two atoms to fill their orbitals.
T- Outer-shell electrons are transferred to fill the inner electron shell of another atom.
O- Electrons from the same atom, but
opposite spins, are paired.
R- Electrons are removed from one atom and transferred to another becoming oppositely charged.
Covalent bonds can be _____ or ______.
Covalent bonds can be polar or nonpolar.
What is electronegativity? What are examples?
A measure of how strongly an atom pulls shared electrons toward itself in a bond.
Examples: Oxygen, which has eight protons and only two electron shells, is among the most electronegative of all elements. Nitrogen, which has one fewer proton, has a somewhat lower electronegativity than oxygen.
Sulfur, carbon, hydrogen, and phosphorus have low and approximately equal electronegativities.
What is a polar covalent bond? What’s an example?
A covalent bond in which electrons are shared unequally between atoms differing in electronegativity. Results in the more electronegative atom having a partial negative charge and the other atom having a partial positive charge.
Example: Both bonds in a water molecule between the hydrogen and oxygen atoms are polar covalent bonds. The partial charges on water molecules—due simply to the difference in electronegativity between oxygen and hydrogen—are one of the primary reasons that life exists. Ammonia (NH3) is a polar covalent bond.
What is a nonpolar covalent bond? What’s an example?
A covalent bond in which electrons are equally shared between two atoms of The same or similar electronegativity.
Example: Because carbon and hydrogen have approximately equal electronegativity, the electrons in a C-H methane bond are shared equally or symmetrically (nonpolar covalent bond). Hydrogen is another example.
What are ionic bonds? Examples?
A chemical bond formed when an electron is completely transferred from one atom to another. This results in ions remaining associated due to their opposite electric charges.
Example: Table salt (Sodium Chloride) (NaCI) is a crypt composed of two ions. CI- and Ha+
What results when electrons aren’t shared equally?
Charges result when electrons are not shared equally.
What are single bonds? Three examples?
A single bond is formed when two atoms share one pair (2 electrons) of electrons.
Examples: Water (H2O), Ammonia (NH3), and Methane (CH4)
What are double bonds? Examples?
A double bond is formed when two atoms share two pairs (4 electrons).
Example: Carbon Dioxide (CO2)
What is a triple bond?
A triple bond is formed when two atoms share three pairs (6 electrons).
Example: Molecular nitrogen (N2)
How is water polar? What bond forms between water molecules?
The electrons from the hydrogens are pulled toward oxygen. Hydrogen bonds form between water molecules.
What are hydrogen bonds? Examples?
A weak interaction between two molecules resulting from the attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge.
Example: When two water molecules approach each other, the partial positive charge on hydrogen attracts the partial negative charge on oxygen. This weak electrical interaction is an example of a hydrogen bond. HF (hydrogen Fluorine), and NH3 (Ammonia) are other examples.
What are two examples of a molecules that dissolves in water? What type of compound is it?
Glucose (C6H12O6) a polar compound and table salt (NaCI) an ionic compound dissolves in water
What type of molecular compound doesn’t dissolve in water?
Nonpolar molecules don’t dissolve in water.
What is hydrophilic? What type of bond are they usually?
Interacting readily with water. Hydrophilic compounds are typically polar compounds containing partially or fully charged atoms.
What is hydrophobic? What type of bond are they?
Not interacting readily with water. Hydrophobic compounds are typically nonpolar molecules.
A ______ forms where water meets a _______, as a result of two ____.
A meniscus forms where water meets a solid surface, as a result of two forces.
What is adhesion?
Water molecules that adhere to the glass and pull upward at the perimeter.
What is cohesion?
Water molecules at the surface form hydrogen bonds with nearby water molecules and resist the upward pull of adhesion.
Water has high ________.
Water has high surface tension.
What is surface tension?
The cohesive force that causes molecules at the surface of a liquid to stick together, resisting deformation of the liquid’s surface.
How does surface tension relate to water?
Because of surface tension, light objects do not fall through the water’s surface.
______ is less _____ than _____.
Solid water (ice) is less dense than liquid water.
Why is solid water less dense than liquid water? (3 ideas)
- In ice, water molecules form a crystal lattice.
- In liquid water, no crystal lattices form.
- Liquid water is denser than ice. As a result, ice floats.
What are antacids? What does that have to do with pH?
Antacids are substances that help neutralize stomach acid. They are usually basic (alkaline) compounds.
Antacids help raises the pH of the stomach by neutralizing the hydrochloric acid (HCl). Makes environment less acidic (less heartburn, indigestion).
How can you calculate a pH or H+ concentration?
pH = -log[H+]
What is acidic?
Solutions that contain acids have a proton concentration pH < 7 because acidic molecules tend to give up protons. Acids give up protons and raise [H3O+], which decreases pH.
What is basic?
Solutions that contain bases have a proton concentration pH > 7 because basic acquire protons when they react with water, which increases pH.
What are the three steps to atmospheric evolution on Earth?
- Early Earth’s atmosphere was made of simple gases like methane, ammonia, and water vapor.
- Energy from things like lightning helped turn these gases into simple organic molecules (amino acids/nucleotides).
- These molecules then combined to form complex molecules like proteins, RNA, and DNA, which are the building blocks of life.
What was the significance of Stanley Miller’s experiment?
- Miller simulated conditions of early Earth’s atmosphere by mixing water (H₂O), methane (CH₄), ammonia (NH₃), and hydrogen (H₂) in a sealed flask, and then subjected the mixture to electric sparks to simulate lightning.
- When Miller analyzed samples, he found large quantities of hydrogen cyanide and formaldehyde.
- It showed that life’s basic molecules could form without the need for life to already exist.
What is an atom? What is its structure?
Has a positively charged nucleus surrounded by negatively charged electrons.
What is an ion? What’s two examples?
An atom or a molecule that has lost or gained electrons and thus carries a full electronic charge, either positive (cation) or negative (anion).
Example: The sodium ion is written NA+ and, like other positively charged ions, is called a cation. Chlorine atoms (Cl), in contrast, tend to gain an electron, filling their outermost shell.
What is a molecule?
When multiple atoms combine together, this creates a molecule.
What is responsible for electronegativity?
It’s a combination of two things—the number of protons in the nucleus and the distance between the nucleus and the valence shell.
What are ionic bonds similar in principle to?
Are similar in principle to covalent bonds, but instead of being shared between two atoms, the electrons in ionic bonds are completely transferred from one atom to the other.
Why do ionic bonds occur?
The electron transfer occurs because it gives each of the two resulting atoms a full valence shell.
What is pH?
A measure of the concentration of protons in a solution and thus of how acidic or basic the solution is.
Why are hydrogen bonds important in biology?
Because of their role in dissolving substances in an aqueous solution.
What are bonds?
Single, double, and triple bonds refer to the number of electron pairs shared between two atoms in a covalent bond.
What is the difference between covalent bonds and ionic bonds?
Covalent bonds share electrons while ionic bonds gain or lose electrons to achieve a full valence shell.
What is chemical evolution?
Simple chemical compounds in the early atmosphere and ocean combined via chemical reactions to form larger, more complex substances, leading to the origin of life.
What are the five properties of water?
- Surface Tension (see flashcard)
- High specific heat capacity- water absorbs and retains heat (a lot of energy needed to change its temp).
- High heat of vaporization- Takes a lot of energy to convert water from liquid to gas.
- Universal solvent- water dissolves many substances due to its polarity
- Density (see flashcards)
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