Chapter 1 Flashcards
Scientific Method
observation question hypothesis experiment anaylze report results
Control
A control is a part of the experiment that does not change
replicates
means they are more likely to be correct. Repeated replication of investigations may turn a hypothesis into a theory. On the other hand, if results cannot be replicated they are likely to be incorrect.
After making careful observations, scientists construct a(n)
hypothesis
Which of the following statements is not true about a hypothesis?
It always withstands the test of experiments
The final outcome of any scientific investigation is “proving” the premise of the question.
False
highest praise you can give to a concept
highest level of trust
huge amouts of predictions and always seem to come out as true
theory
Seeing faces in inanimate objects is an example of
hardwired human bias
The statistical cutoff for scientific significance requres a minimum of a _________ chance that the observed effect is not due to chance.
95%
tentative explanations
testable and falsifiable
estimated idea
hypothesis
Importance of evidence:
We trust it
Belief vs Evidence
Scientific method is far more reliable and strict vs belief can be based on imagination
major elemental constituents (greater than 1%)
oxygen
carbon
hydrogen
nitrogen
calcium
phosoporus
The nucleus of an atom is composed of two subatomic particles, ______________ and ______________.
protons; neutrons
Consequences of being deficient in trace elements in your diet:
body cannot function properly
what are atoms:
basic structure:
smallest particles that retain properties of an element
electrons (-)
Protons (+)
neutrons (no charge)
bohr model of an atom
nucleus - center
contains neutrons and protons
surrounding orbit - electrons
Same number as protons
atomic number
The ___________________ of atoms determine how atoms will react with each other.
electrons
Atoms that bear a positive or negative charge are known as
ions
protons and neutrons added together:
atomic mass
protons cant change
true
when neutrons change
when atoms of an element with different number of neutrons
isotopes
number of electrons = to
= number of protons
electron “shells” (valences)
“distance from the nucleus”
electrons exist in different energetic states
electrons that are further away are at a ____level
higher
inner shell can only hold ____
2 electrons
out sehll can hold ____
up to 8 “octet rule”
period table column:
refer to the # of electrons in the outer most shell of an atom
period table row:
number of shells that ocupied by electrons
how to you make atoms stable (happy)
Lose/gain electrons because atoms like to have their shell full
left side of periodic table tend to ____to gain stability
lose electrons - tend to be metals
column 4 5 6 7tend to _____ to gain stability
gain or share
column 8 tends to ____ to gain stability
unreactive
noble gases
ions
elements that have gained or lost electrons
if you lose electrons you tend to be:
positively charged (metals)
if you gain electrons you tend to be
negative Charge
non metals
bond:
union between electrons in atoms
atoms bond to form:
molecules
covelant bond:
strong bond
share electrons to share outermost shell
very stable
ionic bonds:
weak bond
positive and negative charge bond together
hydrogen bond:
weak bond
when hydrogen covalently bonded to another atom is also attracted to another atom ( typically negative)
Why is carbon special?
carbon has 4 electrons in its outmost shell rather than give or gain it shares almost never behaves ionically behaves covalently among the strongest in the natural world
non-polar molecules
when atoms share electrons equally they create a compound that has no net electrical charge
equally distributed
Hydrogen molecule - non polar stable bond
polar molecules
not an equal distribution - asymetrical
attract opposite charge
electronegativity
bonds that attract opposite charge.
strong polar property pulls
water:
water molecules attracted to each other
high temp stabilizing effect - takes alot of change temp
cohesion - surface tension - pull on itself
solvent - polar property
ice - floats when its a solid
densest as 4 degrees
bases/acids
acid: More Hydrogen H
base: more hydroxide OH
pH scale
measures the number protons or hydogen ions in a fluid
1 change on pH scale =
10x hydrogen change
1 ph (
acidic Highest H+
10 ph
base highest OH-
Donates H+ when dissolved in water
acids (pH < 7)
Accepts H+ when dissolved in water
bases (pH>7)
weak base
strong base
8
12
weak acid
strong acid
6
3
reluctant donors
weak acids
gives up H+ easily when dissolved
strong acids
substances that can combine with A/B and absorb excess ions from keep the PH from changing dramatically
(sodium bicarbonate)
Buffer System
