Chapter 2 Flashcards
Life
ability to replicate and by the presence of some sort of metabolic activity
Biodiversity
variety and variability among all genes, species, and ecosystems
Element
substance that can’t be broken down into any other substances
Everything (matter) is made up of:
atoms
atom
a particle of matter that can’t be further subdivided without losing essential properties
what are the three parts of an atom?
nucleus, and three other parts: electrons, protons, and neutrons
mass
The amount of matter in a particle
electrons weight almost:
nothing; they weight 1/20th of one percent
atomic mass
combined mass of all of the atom’s protons and neutrons
Particles that have the same charge ___ each other
repel
Particles with opposite charges are _____ to each other
attracted
How can we tell elements apart?
by their atomic number, which means how many PROTONS are in the nucleus
Elements differ in their number of ____
protons
element symbol
abbreviation of the element’s name
The mass of an atom is often about double the element’s atomic number
example:
Oxygen mass: 15.99
atomic number: 8
Isotopes
Atoms with the same atomic number (number of protons), but different numbers of neutrons
(extra neutrons or fewer neutrons than the number of protons)
(same protons, different neutrons)
in isotopes, does the charge change? Why?
-no because neutrons don’t have a charge
Does the atom’s mass change in isotopes?
yes, with the loss or addition of another particle in the nucleus
Radioactive
elements/isotopes having an unstable nucleus, breaking down spontaneously, releasing tiny, high-speed particles that carry a lot of energy.
Radioactive atoms turn out to be useful in determining what?
the age of fossils
Of all the elements found on earth, how many are found in your body?
25
The “Big 4” elements consist of:
oxygen, carbon, nitrogen, hydrogen
The “Big 4” make up how much of our body mass?
more than 96%
ions
electrically charged atoms
-number of protons are same, but number of electrons are different
ions have a ___/___ bond
positive/negative
extra electrons mean __ charge and
extra protons mean __ charge
negative; positive
An atom’s ____ determine how and whether the atom will bond with other atoms
electons
The first electron shell holds ___ electrons, and is ___ to the nucleus
2; closest
the second electron shell is ___ away from the nucleus, and can hold up to ___ electrons
farther; 8
how many shells can there be total?
up to 7
If an element doesn’t have eight atoms, how can they get some?
through bonding
Groups of atoms are held together by what?
bonds/molecules
Covalent bonds
STRONG bonds that form when atoms share electons
Double bonds
The sharing of two pairs of electrons between two atoms
Covalent bonds ..
SHARE electrons
Ionic bonds…
TRANSFER electrons
Ionic bond
transferring electrons (now called ions) –oppositely charged ions attract each other and form compound
Hydrogen bonds
link multi-atom MOLECULES togehter
Hydrogen bonds are important for bonding..
molecules together
Ionic and covalent bonds link ___ together
atoms
hydrogen bonds
link multiatom molecules together
-formed between a H in one molecule and another molecule, often O or N
Hydrogen bonds are formed between
the slightly positively charged hydrogen atoms of one molecule and the slightly negatively charged oxygen atom of another
-usually a polar atom and a hydrogen atom
ionic bonds
oppositely charged atoms attract eachother to form a compound, TAKEN not shared (covalent)
electrons determine what?
HOW nd WHETHER the atom will bond with others
Polar
one side is positive, and one is negative
what are polar molecules attracted to?
other polar molecules
-ex: water is the most famous one
are hydrogen bonds strong or weak?
weak
Ionic bonds form _______, while covalent bonds form ________
compounds; molecules
Because of their unequally shared electrons, water molecules are ..
polar
hydrogen bonds make water
cohesive
all life on earth depends on
water
cohesion allows tall trees to exist because
hydrogen bonds allow water molecules to pull up other molecules
water has four unusual properties that are critical, what are they?
cohesion, large heat capacity, low density as a solid, good solvent
When it’s a hot beach day, why is the sand hot but the water isn’t?
hydrogen bonds; hydrogen bonds help resist heating
cohesion
attraction between two like things
adhesion
attraction between two different things
heat capacity is like the ability to absorb heat well without reflecting it
n/a
low density as a solid
ice floats in water
good solvent
Water pries apart ionic bonds, dissolving ionic compounds.
What allows us to remain at a stable temperature despite the weather outisde?
heat capacity
PH Scale: below 7
acidic; more h+ (Less OH-)
above 7
basic; fless h+ (more OH-)
the lower the ___ the greater the ____ on the ph scale
lower;acidity
a decrease of 1 on the pH scale represents a ____-fold increase in the hydrogen ion concentration
ten
ph scale
a way of referring to the acidic, basic, or chemically neutral quality of a fluid.
buffers
chemicals that can quickly absorb excess H+ ions to keep a solution from becoming too acidic, and they can quickly release H+ ions to counteract any increases in OH− concentration.
when blood ph levels become too acidic, a buffer chemical absorbs excess what?
H+ ions
when a blood ph level becomes too basic..
a buffer chemical rleases h+ ions
The pH scale is a direct measure of:
the concentration of hydrogen ions in a solution.
The tendency of water molecules to stick together is called:
cohesion
A chemical compound that releases H+ into a solution is called:
An acid