Studied by 33 PeopleTwo types of Science
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Two types of Science
Induction and Hypothesis based science
Induction Based Science
A predictive generalization Ex. Cell theory - generalizations about cells
Hypothesis Based Science
Deductive Reasoning Hypothesis - explanation for an observations
Occam's Razor
If several explanation work with your evidence, then go for the simplest one. The razor shaves off unnecessary details.
What happens if there is no control in an experiment
No support for hypothesis
Negative Control
Did nothing
Positive Control
A known characterized treatment. It will give a well known effect that is no surprise
Progress in Science
Explanatory power New ideas are formed, and the old rejected
Theories
Need a huge amount of evidence Ex. Theory of natural selection Theories are excepted only because of the evidence behind them.
Replication
Sample size does not equal 1 Has a greater chance of convincing results with replicates Did all results do the same thing ?
Reproducibility
Can others do your experiment? The same results should be from the same experiment, regardless of where and when.
Composition of an Atom
Nucleus has protons (1+) and neutrons (0) Electrons (1-) are in orbitals around nucleus
What defines an atom
The number of protons and the number of neutrons
Isotopes
Have the same atomic number, but a different number of neutrons
What are bonds based on
Electrons
How many bonds does Carbon have
4
How many bonds does Hydrogen have
1
How many bonds does Oxygen have
2
Hydrogen
Smallest atom H+ are important for cellular metabolism
What is left over if Hydrogen loses an electron
Only a proton
Cations
positively charged ion
Anion
a negatively charged ion
Helium
Second smallest atom Two protons atom is mostly empty space Noble gas
What does a chemical bond require
one pair of electrons each atom providing one electron
What type of bond is N
3
Non polar
no partial charge on atoms Share equal
Covalent
Bonds are shared
Electronegativity (EN)
The ability of some atoms to attract electrons to itself
Polar Covalent Bonds
Shared unequally in a covalent bonds - if moderate difference
Polar
Refers to the fact that partial charges due to unequal sharing
What is water held together by
two polar bonds - example of a polar molecule
Examples of Non polar covalent bonds
O-H, N-H, 0-C, N-C
Ionic Bonds
No sharing Taking electrons (higher EN) Ex. Salts Form between between atoms with different EN
Hydrogen Bonds
Constantly breaking and reforming (transient) Consequence of polar covalent bonds containing hydrogen Water molecules stick together due to hydrogen bonds
Water
Cells are 80% water Water is the solvent of life
Universal Solvent
Does not exist
What does water exhibit
Cohesion
Hydrophilic
Water liking Polar/Charged
Hydrophobic
Water fearing Non polar covalent bonds not soluble in water
What is water attracted to
Large polar/ charged molecules Ex. Sugars
What is more soluble
Small hydrophilic molecules
Large polar molecule solubility
They are also hydrophilic But can be too big to be soluble
What are Hydrophobic molecules composed of
Non polar covalent bonds Ex. C-C, C-H Fats are hydrophobic
What can water do
Reverse disassociate
Strong acid
Complete dissociation unlike equilibrium for water dissociation HCl-->H+ +Cl-
Acidity
protons (H+) More than High acidity
pH
Measure of acidity -log[H+]
What is pH 7
Neutral/water
Higher than 7 pH
Acidic