2.1 Basic Chemistry (+ Image Occlusion)

Chemicals

Chemicals make up the body's structures.

interactions

The __________ of chemicals with one another are responsible for the body's functions.

Chemistry

__________ is the scientific discipline concerned with the atomic composition of substances and the reactions they undergo.

matter

All living and nonliving things are composed of ________, which is anything that occupies space and has mass.

Mass

__________ is the amount of matter in an object.

Weight

__________ is the gravitational force acting on an object of a given mass.

kilogram (kg)

The international unit for mass is the __________________.

1 gram (g)

An object with 1/1000 the mass of the standard kilogram is said to have a mass of __________.

atom

An ________ is the smallest particle of an element that has the chemical characteristics of that element.

one

An element is composed of atoms of ___ kind(s).

structure, organization, behavior

The characteristics of matter result from the __________, ______________, and __________ of atoms.

subatomic particles

Atoms are composed of __________________.

neutrons, protons, electrons

The three major types of subatomic particles are __________, __________, and __________.

neutron

A __________ has no electrical charge.

proton

A __________ has one positive charge.

electron

An __________ has one negative charge.

equal, cancel

Since each atom has an ______ number of protons and electrons, the positive and negative charges ______ each other.

Electrical charge

__________________ is the tendency of particles to be attracted to or repulsed from each other.

opposite, same

Particles with __________ charge are attracted to each other, while particles with the __________ charge are repulsed from each other.

nucleus

Protons and neutrons are found in the center of the atom, which is called the __________.

kernel, inner part

The term nucleus means "________________".

electron cloud

Electrons are found in an __________________ and are constantly orbiting the nucleus.

protons

Each element is uniquely defined by the number of __________ in the atoms of that element.

atomic number

The number of protons in each atom is called the __________.

mass number

The __________ of an element is determined by adding the number of protons and neutrons in each atom.

Isotopes

__________ are two or more forms of the same element that have the same number of protons and electrons, but have a different number of neutrons.

radioactive

The most familiar isotopes are those that are __________, which are used in nuclear medicine and other applications.

chemical bond

A __________ __________ is an association between two atoms formed when the outermost electrons are transferred or shared between atoms.

electrons

The chemical behavior of an atom is dependent on its __________.

energy levels

The electron cloud around an atom's nucleus is organized into different __________ depending on the distance of an electron from the nucleus.

electron shells

For simplicity, the energy levels are often drawn as concentric rings, called __________ around the nucleus.

2

The innermost shell holds a maximum of ___ electrons.

8

All remaining shells hold a maximum of ___ electrons.

valence shell

The outermost shell is called the __________ __________.

valence shell

The number of electrons in the __________ __________ determines an atom's chemical behavior.

octet

If an atom's valence shell is not at its maximum, it will form bonds with other atoms to achieve a full valence shell, called an __________.

octet rule

Most atoms follow the __________ __________-the tendency of atoms to combine with other atoms until each has 2 electrons in its valence shell.

transferring, sharing

Atoms achieve an octet by __________ or __________ electrons between atoms.

Electronegativity

__________________ is the ability of the atom's nucleus to pull electrons toward it.

strong

Atoms with a __________ electronegativity are those with 6 or 7 electrons in the valence shell.

weak

Atoms with a __________ electronegativity are those with only 1 or 2 electrons in the valence shell.

transfer

In a chemical bond, atoms with very different electronegativity tend to __________ atoms.

share

In a chemical bond, atoms with similar electronegativities are likely to __________ the electrons.

ion

An __________ is an atom carrying an electrical charge because of a loss or gain of 1(+) electrons.

positively

When a weakly electronegative atom loses an electron, it has one more proton than it has electrons and is __________ charged.

negatively

After an atom gains an electron, it has one more electron than it has protons and is __________ charged.

positively, (Na+)

A sodium atom (Na) can lose an electron to become a __________ charged sodium ion __________.

negatively, Cl-

A chlorine atom (Cl) can accept an electron to become a __________ charged chloride ion __________.

ionic

An __________ bond forms when electrons are transferred between atoms, creating oppositely charged ions.

sodium chloride, NaCL

Na+ and Cl- are held together by ionic bonding to form an array of ions called __________ __________ (__________).

covalent

A __________ bond forms when atoms share one or more pairs of electrons.

sharing

The __________ of electrons occurs because the atoms have similar electronegativities.

molecule

A __________ is two or more atoms chemically combined to form a structure that behaves as an independent unit.

nonpolar

A __________ covalent bond forms when the electrons are shared equally between the nuclei.

nonpolar

A __________ molecule is formed by nonpolar covalent bonds when there is equal sharing of electrons between atoms of the molecule.

neutral

A nonpolar molecule carries a __________ charge.

polar

In cases where the two atoms involved in a covalent bond have different electronegativities, a __________ covalent bond will form.

polar

Polar covalent bonds can result in __________ molecules, which are electrically asymmetric.

compound

A __________ is a substance resulting from the chemical combination of two or more different types of atoms.

Covalent

Covalent compounds, in which different types of atoms are held together by covalent bonds, are molecules because the sharing of electrons results in distinct units.

Ionic

Ionic compounds, in which ions are held together by the force of attraction between opposite charges, are not molecules because they do not consist of distinct units.

Intermolecular forces

____________________________ are the weak electrostatic attractions that exist between opposite charged parts of molecules, or between ions and molecules.

no

There is ___ exchange of electrons in intermolecular forces.

positive, negative

Intermolecular force results from the attraction of the __________ end of one polar molecule to the __________ end of another polar molecule.

hydrogen

If the positively charged hydrogen of one molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another molecule, a __________ bond forms.

the same molecule

Hydrogen bonds form intramolecular bonds between water molecules and within __________________.

proteins, nucleic acids

Intramolecular hydrogen bonds form the more complex structure of __________ and __________ and help stabilize their final three-dimensional shapes.

dissociate

When ionic compounds dissolve in water, their ions __________, or separate, from each other.

electrolytes

Dissociated ions are sometimes called __________ because they have the capacity to conduct an electrical current.

intact

When molecules dissolve in water, the molecules remain __________ even though they are surrounded by water molecules.