Chapter 2 Flashcards
All living things consist of 1), which is
anything that occupies space and has 2).
2) is the amount of matter in any object, which does not change.
1) matter 2)mass
? , the force of
gravity acting on matter, does change.
Weight
All forms of matter—both living
and nonliving—are made up of a limited number of building blocks called ?.
chemical elements
Each named element is designated by a ?, one or two letters of the element’s name in English, Latin, or another language. Examples of chemical symbols are H for hydrogen, C for carbon, O for oxygen, N for nitrogen,
Ca for calcium, and Na for sodium .
chemical symbol
Twenty-six different chemical elements normally are present in your body. Just four elements, called the ?, constitute about 96% of the body’s mass: oxygen, carbon, hydrogen, and nitrogen.
major elements
Eight others elements, called ? , contribute about 3.6% to the body’s mass:calcium, phosphorus (P), potassium (K), sulfur (S), sodium, chlorine (Cl),magnesium (Mg), and iron (Fe; ferrum= iron).
the lesser elements,
An additional 14 elements—
the ? —are present in tiny amounts.
trace elements
Each element is made up of ? the smallest units of matter that retain the properties and characteristics of the element.
atoms
Dozens of different ? compose individual atoms.
subatomic particles
The dense central core of an atom is its 1). Within the nucleus are positively charged 2) and uncharged (neutral) 3). The tiny, negatively charged 4) move about in a large space surrounding the nucleus.
1) nucleus 2)protons (p+) 3) neutrons (n0) 4) electrons (e−)
Even though their exact positions cannot be predicted, specific groups of electrons are most likely to move about within certain regions around the nucleus. These regions, called ?, may be depicted as simple circles around the nucleus.
electron shells
The number of protons in the nucleus of an atom is an atom’s?
atomic number
The ? of an atom is the sum of its protons and neutrons.
mass number
? are atoms of an element that have different numbers of neutrons and therefore different mass numbers.
Isotopes
Certain isotopes called ? are unstable; their nuclei decay (spontaneously change) into a stable configuration.
radioactive isotopes (radioisotopes)
The ? of an isotope is the time required for half of the radioactive atoms in a sample of that isotope to
decay into a more stable form.
half-life
The standard unit for measuring the mass of atoms and their subatomic particles is a ?, also known as an atomic mass unit (amu).
dalton
The ? of an element is the average mass of all
its naturally occurring isotopes.
atomic mass (also called the atomic weight)
A ? is a substance that contains atoms of two or
more different elements.
compound
A ? is an atom or group of atoms with an
unpaired electron in the outermost shell.
free radical
If an atom either gives up or gains electrons, it becomes an ?. An ? is an atom that has a positive or negative charge because it has unequal numbers of protons and electrons.
ion
? is the process of giving up or gaining electrons
Ionization
When two or more atoms share electrons, the resulting combination is called a ?
molecule ; . A molecule may consist of two atoms of the same kind,such as an oxygen molecule
The forces that hold together the atoms of a molecule or a compound are ?.
chemical bonds
The likelihood that an atom will form a chemical
bond with another atom depends on the number of electrons in its outermost shell, also called the ?
valence shell
The force of attraction that holds together ions with opposite charges is an ?.
ionic bond
An ionic compound that breaks apart into positive and
negative ions in solution is called an ?
electrolyte
When a ? forms, two or more atoms share electrons
rather than gaining or losing them.
covalent bond ; The larger the number of electron pairs shared between two atoms, the stronger the covalent bond.
A ? results when two atoms share one electron pair. For example, a molecule of hydrogen forms when two hydrogen atoms share their single valence electrons which allows both atoms to have a full valence shell at least part of the time.
single covalent bond
A ? results when two atoms share two pairs of
electrons, as happens in an oxygen molecule.
double covalent bond
A ? occurs when two atoms share three pairs of electrons, as in a molecule of nitrogen .
triple covalent bond
In some covalent bonds, two atoms share the electrons equally—one atom does not attract the shared electrons more strongly than the other atom. This type of bond is a ?
nonpolar covalent bond
In a ?, the sharing of electrons between two
atoms is unequal—the nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom.
polar covalent bond ; A very important example of
a polar covalent bond in living systems is the bond between oxygen and hydrogen in a molecule of water
A ? forms when a hydrogen atom
with a partial positive charge (δ+) attracts the partial negative charge (δ−) of neighboring electronegative atoms, most oft en larger oxygen or nitrogen atoms
hydrogen bond ; hydrogen bond do establish important links between molecules or between different parts of a large molecule, such as a protein or
nucleic acid
The hydrogen bonds that link neighboring water molecules give water considerable cohesion, the tendency of like particles together. The cohesion of water molecules creates a very high ? a measure of the difficulty of stretching or breaking the surface of a liquid.
surface tension
A ? occurs when new bonds form or old bonds break between atoms.
chemical reaction
? is the capacity to do work.
Energy
Two principal forms of energy
are 1), energy stored by matter due to its position,
and 2) the energy associated with matter in motion
1) potential energy 2) kinetic energy,
? is a form of potential energy that is stored in the bonds of compounds and molecules.
Chemical energy
Although energy can be neither created nor
destroyed, it may be converted from one form to another. This principle is known as the ?
law of conservation of energy
Chemical bonds represent stored chemical energy, and chemical reactions occur when new bonds are formed or old bonds are broken between atoms. The overall reaction may either release energy or absorb energy. 1) release more energy than they absorb. By contrast, 2)
absorb more energy than they release.
1) Exergonic reactions 2) endergonic reactions
The collision energy needed to break the chemical bonds of the reactants is called the ? of the reaction .
activation energy
? : The more particles of matter present in a confined
space, the greater the chance that they will collide.
Concentration
?: As ? rises, particles of matter move about
more rapidly.
Temperature
? are chemical compounds that speed up chemical reactions by lowering the activation energy needed for a reaction to occur
Catalysts
