bio c2 quiz

CHON make up _ of living matter

96%

Organisms are composed of ___, which is anything that takes up space and has mass (ex. metals, gases, organisms)

matter

Matter is made up of ___. An ___ is a substance that cannot be broken down to other substances by chemical reactions

elements; element

A ___ is a substance consisting of two or more different elements combined in a fixed ratio (ex. NaCl)

compound

Having ____: A compound has characteristics different from those of its elements

emergent properties

Of the 92 natural elements, about 20-25% are that an organism needs to live a healthy life and reproduce (plants 17, humans 25)

essential elements

Explain how table salt has emergent properties

Table salt (NaCl) is made of sodium (a metal) and chlorine (a toxic gas). Together they form an edible substance with properties different from its elements.

Is a trace element an essential element? Explain.

Yes. Even though needed in small amounts, deficiency can cause problems (e.g., iodine deficiency causes goiter).

In humans, iron is a trace element required for hemoglobin. What might be the effects of an iron deficiency?

Fatigue and other effects of low blood oxygen (anemia).

Explain how natural selection might have played a role in evolution of species tolerant of serpentine soils.

Variations that allowed survival in serpentine soils led to reproduction. Over generations, serpentine-tolerant species evolved.

An _ is the smallest unit of matter that still retains the properties of an element.

atom

Protons and neutrons are packed in a dense core called the . Protons give it a positive charge. Electrons form a “” around it.

atomic nucleus; cloud

For atoms, molecules, and subatomic particles, we use a unit of measurement called the __ (same as amu).

dalton

This number of protons, unique to each element, is called the _. (also tells # of electrons)

atomic number

The total number of protons and neutrons in an atom’s nucleus is the __.

mass number

The total mass of an atom is called its _.

atomic mass

Different atomic forms of the same element are called _.

isotopes

A _ is one in which the nucleus decays spontaneously, giving off particles and energy (ex. 14C).

radioactive isotope

A “parent” isotope decays into its “daughter” isotope at a fixed rate, called the _.

half-life

Scientists use to measure isotopes and calculate how many half-lives have passed since a fossil or rock formed.

radiometric dating

_ is defined as the capacity to cause change—for instance, by doing work.

energy

_ is the energy that matter possesses because of its location or structure.

potential energy

Electrons are found in different , each with characteristic distance and energy.

electron shells

Outer electrons are called ___ and the outermost shell is the __.

valence electrons; valence shell

The 3D space where an electron is found 90% of the time is called an .

orbital

A lithium atom has 3 protons and 4 neutrons. What is its mass number?

7

Write the chemical symbol for radioactive nitrogen with 7 protons and 8 neutrons.

¹⁵₇N

How many electrons does fluorine have? How many shells? Which orbitals? How many needed to fill valence shell?

9 electrons, 2 shells, orbitals 1s 2s 2p, needs 1 electron to fill valence shell

In a periodic table, what do elements in the same row have in common? Column?

Same row → same # of electron shells. Same column → same # of valence electrons.

Interactions between atoms that result in attraction are called ___.

chemical bonds

A is the sharing of a pair of valence electrons by two atoms.

covalent bond

Two or more atoms held together by covalent bonds constitute a ___.

molecule

A structural formula line (H–H) represents a ___.

single bond

Two oxygen atoms sharing two pairs of electrons form a ___.

double bond

An atom’s bonding capacity, equal to electrons needed to complete valence shell, is its .

valence

The attraction of an atom for electrons in a covalent bond is called ___.

electronegativity

Equal sharing of electrons is a __ covalent bond.

nonpolar

Unequal sharing of electrons is a __ covalent bond.

polar

Oppositely charged atoms/molecules are called _.

ions

A positively charged ion is a ; a negatively charged one is an .

cation; anion

The attraction between cations and anions is an ___.

ionic bond

Compounds formed by ionic bonds are called __, or ___.

ionic compounds; salts

A noncovalent attraction between hydrogen and an electronegative atom is a .

hydrogen bond

Everchanging weak attractions between molecules are called __.

van der Waals interactions

Why does H–C=C–H not make sense chemically?

Each carbon only has 3 bonds, violating the octet rule.

What holds atoms together in MgCl₂ crystals?

Ionic bonds

Why should pharmaceutical researchers know 3D shapes of molecules?

Shape determines recognition/response; mimicking shapes helps design treatments.

Making and breaking of bonds, changing composition of matter, are called ___.

chemical reactions

Starting materials are __, resulting materials are ____.

reactants; products

The point where forward and reverse reactions balance is ___.

chemical equilibrium

Reaction: 2H₂ + O₂ → 2H₂O. What structures are drawn?

Lewis dot structures of hydrogen and oxygen bonding to form water.

At equilibrium, which reaction is faster? Forward or reverse?

Neither; they occur at the same rate.

Write the equation for cellular respiration. How does it relate to breathing?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy. We inhale O₂ and exhale CO₂, like in cellular respiration.