A&P1 chapter 2

What is matter?

Matter is anything that has mass and occupies space.

What are the three forms of matter?

Solid, liquid, and gas; examples include bone, blood, and oxygen.

What is an atom?

The smallest particle of an element that exhibits the chemical properties of that element.

What is an element?

A pure substance consisting of one type of atom that cannot be broken down into simpler substances by ordinary chemical means.

How many naturally occurring elements make up matter, according to the PowerPoint?

92 naturally occurring elements.

What is the periodic table?

A chart that organizes elements by atomic number and groups elements with related chemical properties.

What are the three main subatomic particles?

Protons, neutrons, and electrons.

What is a proton?

A positively charged subatomic particle with a mass of approximately 1 atomic mass unit (amu), located in the nucleus.

What is a neutron?

A subatomic particle with no electrical charge and a mass of approximately 1 amu, located in the nucleus.

What is an electron?

A negatively charged subatomic particle with about 1/1800 the mass of a proton or neutron, found in regions around the nucleus.

Where are protons and neutrons located?

In the nucleus of an atom.

Where are electrons located?

In electron orbitals or regions surrounding the nucleus.

What is the electrical charge of a proton, neutron, and electron?

Proton: +1; neutron: 0; electron: −1.

Which subatomic particles account for most of an atom's mass?

Protons and neutrons.

What is an element's chemical symbol?

A one- or two-letter abbreviation used to represent an element, such as C for carbon.

What is the atomic number?

The number of protons in an atom's nucleus.

What does the average atomic mass represent?

The weighted average mass of an element's naturally occurring isotopes, largely reflecting their protons and neutrons.

How do you calculate the number of neutrons using the mass number and atomic number?

Subtract the atomic number from the mass number: neutrons = mass number − atomic number.

How do you determine the number of electrons in a neutral atom?

The number of electrons equals the number of protons, which equals the atomic number.

How many protons, neutrons, and electrons are in a neutral sodium-23 atom?

11 protons, 12 neutrons, and 11 electrons.

What is an electron shell?

An energy level surrounding the nucleus that can hold a limited number of electrons.

How many electrons fit in the first and second electron shells, according to the PowerPoint?

The first shell holds 2 electrons, and the second shell holds up to 8.

In what order are electron shells filled?

Shells closest to the nucleus fill before shells farther away.

What is a valence shell?

The outermost electron shell of an atom.

What are valence electrons?

Electrons in an atom's outermost shell that are especially important in chemical bonding.

What are isotopes?

Atoms of the same element that have the same number of protons but different numbers of neutrons.

How do isotopes of an element differ?

They have different numbers of neutrons and different atomic masses, but generally have the same chemical characteristics.

How many neutrons are in carbon-12, carbon-13, and carbon-14?

Carbon-12 has 6 neutrons, carbon-13 has 7, and carbon-14 has 8.

Why is average atomic mass usually not a whole number?

It is a weighted average of the masses of the element's naturally occurring isotopes.

What is a radioisotope?

A radioactive, unstable isotope that releases radiation as it decays toward a more stable form.

What types of radiation are identified in the PowerPoint?

Alpha particles, beta particles, and gamma rays.

What is physical half-life?

The time required for 50% of a radioisotope to decay into a stable form.

What is biological half-life?

The time required for half of a substance introduced into the body to be eliminated; it can apply to radioactive and nonradioactive substances.

How are radioisotopes used in thyroid imaging?

Radioactive iodine can be taken up by thyroid cells and traced using scintigraphy; areas taking up less iodine may help reveal a nodule.

What is the octet rule?

Atoms tend to gain, lose, or share electrons to achieve a stable outer shell with eight electrons.

Why are noble gases generally chemically unreactive?

Their outer electron shells are already full, making them relatively stable.

What is a chemical compound?

A stable association of two or more elements combined in a fixed ratio.

What are the two major categories of chemical compounds described in the PowerPoint?

Ionic compounds and molecular compounds.

What is an ion?

An atom or group of atoms with a net electrical charge because electrons have been gained or lost.

What is a cation?

A positively charged ion formed when an atom or group of atoms loses electrons.

What is an anion?

A negatively charged ion formed when an atom or group of atoms gains electrons.

How does losing an electron affect an atom's charge?

It makes the atom more positive because it has more protons than electrons.

How does gaining an electron affect an atom's charge?

It makes the atom more negative because it has more electrons than protons.

What happens when sodium forms a sodium ion?

Sodium loses one electron, leaving 11 protons and 10 electrons and producing a +1 charge (Na⁺).

What happens when chlorine forms a chloride ion?

Chlorine gains one electron, leaving 17 protons and 18 electrons and producing a −1 charge (Cl⁻).

What is a polyatomic ion?

A charged group made up of more than one atom, such as bicarbonate or phosphate.

What is an ionic bond?

The electrostatic attraction between oppositely charged ions.

What is an ionic compound?

A compound consisting of positively and negatively charged ions held together by ionic attractions, commonly arranged in a crystal lattice.

How does table salt (NaCl) form?

Sodium transfers an electron to chlorine, forming Na⁺ and Cl⁻ ions that attract each other.

How does magnesium chloride (MgCl₂) form?

Magnesium loses two electrons, one to each of two chlorine atoms, forming Mg²⁺ and two Cl⁻ ions.

Can two cations or two anions form an ionic bond with each other?

Not through attraction between those like charges; ionic attraction occurs between oppositely charged ions.

Why are ions important in the human body?

Ions contribute to physiological functions and are present in body fluids; examples include sodium, chloride, and bicarbonate.

What is a covalent bond?

A chemical bond in which atoms share one or more pairs of electrons.

What is a molecule?

Two or more atoms held together by chemical bonds.

What is a molecular compound?

A compound whose atoms of different elements are joined by covalent bonds, such as carbon dioxide (CO₂).

How does a molecular formula differ from a structural formula?

A molecular formula gives the types and numbers of atoms; a structural formula also shows how the atoms are arranged or connected.

What is an isomer?

One of two or more molecules with the same molecular formula but a different arrangement of atoms.

What are three examples of isomers with the formula C₆H₁₂O₆?

Glucose, galactose, and fructose.

Why can isomers have different chemical properties?

Their atoms are arranged differently, affecting the molecule's shape and interactions.

How many covalent bonds can hydrogen, oxygen, nitrogen, and carbon commonly form?

Hydrogen forms 1, oxygen 2, nitrogen 3, and carbon 4 covalent bonds.

What is a single covalent bond?

A covalent bond in which two atoms share one pair of electrons.

What is a double covalent bond?

A covalent bond in which two atoms share two pairs of electrons.

What is a triple covalent bond?

A covalent bond in which two atoms share three pairs of electrons.

What is electronegativity?

The relative attraction an atom exerts on shared electrons in a chemical bond.

What is a nonpolar covalent bond?

A covalent bond in which electrons are shared equally or nearly equally between atoms.

What is a polar covalent bond?

A covalent bond in which electrons are shared unequally, creating partial charges.

How does electronegativity generally change across the periodic table?

It generally increases from left to right across a row and from bottom to top within a column.

How does the electronegativity of hydrogen, carbon, nitrogen, and oxygen compare?

From least to greatest: hydrogen < carbon < nitrogen < oxygen.

What partial charges develop in a polar covalent bond?

The more electronegative atom develops a partial negative charge (δ−), while the less electronegative atom develops a partial positive charge (δ+).

Why is a carbon-hydrogen bond often treated as nonpolar in the PowerPoint?

The difference in electronegativity is small, so the electrons are treated as shared relatively evenly.

What is a polar molecule?

A molecule with an uneven distribution of electrical charge, often due to polar bonds and an overall arrangement that does not cancel their partial charges.

What is a nonpolar molecule?

A molecule with no overall separation of charge; it may contain nonpolar bonds or polar bonds whose partial charges cancel.

Why is water a polar molecule?

Oxygen attracts the shared electrons more strongly than hydrogen, and the molecule's shape leaves an uneven distribution of charge.

Why is carbon dioxide a nonpolar molecule despite having polar bonds?

Its two polar carbon-oxygen bonds are arranged symmetrically, so their partial charges cancel overall.

What is an amphipathic molecule?

A molecule with both polar and nonpolar regions, such as a phospholipid.

What are intermolecular attractions?

Weak attractions between separate molecules that help influence the shape and behavior of complex molecules.

What is a hydrogen bond?

An attraction between a partially positive hydrogen atom in one polar molecule and a partially negative atom in another molecule.

Why are hydrogen bonds important even though each is weak?

Many hydrogen bonds acting together can have a substantial effect on molecular structure and properties, including those of water, DNA, and proteins.

What are temporary electron-distribution attractions?

Weak attractions caused by momentary uneven distributions of electrons that can induce uneven distributions in nearby molecules.

What are hydrophobic interactions?

Tendencies of nonpolar molecules or regions to cluster together in water, reducing their contact with water.

What is an organic molecule in the PowerPoint's classification?

A molecule containing carbon that is or was part of a living organism.

What is an inorganic molecule in the PowerPoint's classification?

A molecule classified outside the organic category, including water, salts, acids, and bases.

What proportion of the human body by weight is water, according to the PowerPoint?

Approximately two-thirds.

How is a water molecule constructed?

One oxygen atom is covalently bonded to two hydrogen atoms (H₂O).

What partial charges occur in a water molecule?

Oxygen has a partial negative charge, and each hydrogen has a partial positive charge.

How many hydrogen bonds can one water molecule form with neighboring molecules, according to the PowerPoint?

Up to four hydrogen bonds.

What are the three phases of water?

Solid (ice), liquid (water), and gas (water vapor).

Why is water liquid at typical body and room temperatures?

Hydrogen bonding between water molecules requires energy to disrupt, helping water remain liquid under these conditions.

How does water help transport substances in the body?

Many substances dissolve in water and can move through body fluids.

How does water provide lubrication and cushioning?

It reduces friction between body structures and helps absorb sudden forces from movement.

How does water help the body excrete waste?

Waste substances that dissolve in water can be carried and eliminated from the body.

What is cohesion?

Attraction between water molecules, largely due to hydrogen bonding.

What is surface tension?

The inward pulling effect created by cohesive forces at the surface of water.

Why is pulmonary surfactant important?

It reduces surface tension in the moist air sacs of the lungs, helping prevent them from collapsing.

What is adhesion?

Attraction between water molecules and substances other than water.

What is temperature?

A measure related to the kinetic energy of the atoms or molecules within a substance.

What is specific heat?

The amount of energy needed to raise the temperature of 1 gram of a substance by 1°C.

Why does water have a high specific heat?

Energy is required to disrupt hydrogen bonds, so water can absorb considerable heat before its temperature rises substantially.

What is heat of vaporization?

The heat required to convert 1 gram of a liquid into a gas.

How does water's high heat of vaporization help cool the body?

Evaporating sweat requires heat energy, which is taken from the body and helps lower its temperature.