Unit 2: Chemistry of Life Quiz Review

What is a compound?

2 or more atoms that are chemically combined (mixed substances)

What is H20's pH?

7 means it's neutral

explain the three types of nitrogen fixation

Atmospheric Fixation: lightning splits apart a nitrogen gas molecule. atoms bond to other gases and water molecules make their way to soil Industrial Fixation: industries convert natural nitrogen containing compounds into fertilizers under intense temps. Biological Fixation: bacteria living in the soil near the roots of plants (called legumes) convert nitrogen gas into a form of nitrogen that plants can use

What is the smallest unit of matter?

Atom

when water breaks apart, what two ions form?

Hydrogen (H+) and hydroxide (OH-)

What is the center of the atom called?

Nucleus

What is the electron cloud/orbital?

Where electrons are found, an estimate b/c we are never sure where exactly they are since electrons are so small

What is capillary action?

ability of water to flow in narrow spaces without assistance created by a combo of cohesion and adhesion

What is specific heat?

amount of heat energy needed to raise the temp. of 1 gram of a substance by 1 degree Celsius

What is matter?

anything that has mass or takes up space

Explain positive ions

atoms give up electrons to another atom

Explain negative ions

atoms that receive electrons from another atom

what is denitrification?

bacteria return nitrogen to the atmosphere as a gas

What are covalent bonds?

bond between atoms that SHARE one or more pairs of electrons to maintain stability

most living things have what to balance pH

buffers

what are two ways CO2 are released back into the atmosphere

burning fossil fules cutting down/burning forests erupting volcanoes

What are elements?

can't be broken down anymore on the periodic table 25 elements are important to life 95% of all life is made of carbon, hydrogen, oxygen, phosphorus, nitrogen, and sulfur

all living things are what based

carbon

Explain chemical reactions

chemical reactions either release energy or require energy Exergonic: reaction releases energy Endergonic: reaction requires energy

What is a molecule?

compound formed by covalent bonds (atoms sharing electrons)

organisms must balance the what of dissolved things in cells?

concentration

Describe acids

donate hydrgen ions ionic compounds

What is high heat of vaporization?

due to the network of hydrogen bonding present between water molecules, water requires a high input of heat energy to convert 1 gram of liquid water into water vapor

What is surface tension?

elastic-like force on the surface of water that has the effect of making a stronger "skin" on the top of the water caused by cohesion

what maintain a stable internal environment? (homeostasis)

living things

Describe bases

lose hydroxides ionic compounds

What is recycled within and between ecosystems?

matter

what does pH mean?

measure of how acidic or alkaline (basic) a solution/substance is

What are electrons?

negative charged particles (-)

What are neutrons?

neutral charged particles (no charge)

What do buffers do to pH

neutralize changes in pH and counteract the effects of a strong acid or base

what converts nitrogen gas into nitrates the plants can use (hint: called nitrogen fixation)

nitrogen-fixing bacteria

What is an atomic number?

number of protons (equal to number of electrons in a neutrally charged element) each element has a different atomic number atomic numbers are always whole numbers

What is an atomic mass?

number of protons and neutrons decimal number you must take the average to find the number

_________ are all of the chemical substances that an organism needs to survive

nutrients

What is the Octet Rule?

only two electrons in the innermost shell only 8 in the next 2 shells

What is a valence shell?

outermost cell of an atom

many organisms use what to break down carbohydrates for energy during cellular respiration

oxygen

Describe oxygen and hydrogen in the water molecule

oxygen pulls on shared electrons more, creating smaller charges within the molecule oxygen becomes the negative "pole" hydrogens become the positive "pole"

How is a water molecule bonded together?

polarity

What are protons?

positive charged particles (+)

all organisms need nitrogen to make what two things

protein nucleic acids

A central nucleus is made up of what?

protons and neutrons (orbitals contain electrons)

What is the Lewis Dot Structure? (or diagram)

shows electrons in valence

Water is known as a universal _______

solvent it can dissolve many substances due to its polarity helps water carry nutrients into a cell and waste out of the cell

What is cohesion?

tendency of water molecules to stick to each other

What is adhesion?

tendency of water molecules to stick to other hydrophilic surfaces

What is an Ionic Bond?

the combining of ions of opposite charges ions TRANSFER electrons to maintain stability

What are radioactive isotopes?

unstable will eventually decay release particles and energy

What are isotopes?

varied forms of an element that have a different number of neutrons

What is evaporative cooling?

water absorbs energy (heat) when it evaporates allows organisms to release excess heat

What is transpiration?

water evaporates from leaves of plants