Lecture Series 2 Basic Chemistry Vocabulary

Question 1

atom

Answer 1

The smallest unit of an element that retains the element’s distinctive properties. Atoms are the building blocks of all matter.

Question 2

proton

Answer 2

A subatomic particle, it is the positively charged particle found in the nucleus of an atom.

Question 3

neutron

Answer 3

A subatomic particle, it is an electrically neutral particle found in the nucleus of an atom.

Question 4

electron

Answer 4

A subatomic particle, it is a negatively charged particle found outside the nucleus of an atom.

Question 5

atomic number

Answer 5

The number of protons in an atom’s nucleus.

Question 6

molecule

Answer 6

an association of atoms held together by nuclear bonds

Question 7

element

Answer 7

a pure substance that has distinctive physical and chemical properties, and cannot be broken down into other substances by ordinary chemical methods.

Question 8

ion

Answer 8

an atom that has lost or gained electrons and therefore is either negatively or positively charged

Question 9

isotope

Answer 9

two or more forms of an element that have the same number of protons but different numbers of neutrons

Question 10

chemical reaction

Answer 10

the process of breaking existing chemical bonds and creating new ones

Question 11

chemical bond

Answer 11

a force that holds two atoms together

Question 12

ionic bond

Answer 12

the chemical attraction between a negatively charged ion and a positively charged ion

Question 13

covalent bond

Answer 13

the sharing of electrons between two atoms

Question 14

polar molecule or dipole

Answer 14

a molecule whose electrical charge is shared unevenly, with some regions being electrically negative and others being electrically positive

Question 15

hydrogen bonding

Answer 15

the weak electrical attraction between a hydrogen atom with a partial positive charge and a neighboring atom with a partial negative charge

Question 16

pH scale

Answer 16

a logarithmic scale that indicates the concentration of hydrogen ions. The scale goes from 0-14 with 0 representing an extremely high concentration of free H ions and 14 representing the lowest concentration.

Question 17

hydrophobic

Answer 17

literally “water fearing.” Excluded from water

Question 18

hydrophilic

Answer 18

literally “water loving.” Soluble in water.

Question 19

atomic nucleus

Answer 19

the small, dense region consisting of protons and neutrons at the center of an atom

Question 20

compound

Answer 20

a mixture that is composed of two or more separate elements and contains more than one type of atom bonded together, ex. phytochemicals and buffers

Question 21

electron shell

Answer 21

the outside part of an atom around the atomic nucleus. It is a group of atomic orbitals with the same value of the principal quantum number n. Electron shells have one or more electron subshells, or sublevels

Question 22

electron fill order

Answer 22

First electron shell can hold up to 2 e-•2nd electron shell can hold up to 8e-•3rd electron shell can hold up to 18e-•4th electron shell can hold up to 32e-•However, 3rd and 4th shells will not fill with more than 8 electrons until all 18 or 32.

Question 23

electron frequency

Answer 23

the energy of an electron expressed as light

Question 24

free radicals

Answer 24

a molecule used within the biochemical pathways of cells that has lost an electron and therefore will steal an electron from the closest molecule; can set off a chain reaction – resulting in cell death and even tissue damage

Question 25

metallic bond

Answer 25

Electron pooling, the force of attraction between valence electrons and the metal atoms. It is the sharing of many detached electrons between many positive ions, where the electrons act as a “glue” giving the substance a definite structure. It is unlike covalent or ionic bonding

Question 26

polar covalent bond

Answer 26

a particular type of covalent bond. In a polar covalent bond, the electrons shared by the atoms spend a greater amount of time, on the average, closer to the Oxygen nucleus than the Hydrogen nucleus; When two atoms are bonded and their nucleus contains different numbers of protons

Question 27

nonpolar covalent bond

Answer 27

a type of chemical bond where two atoms share a pair of electrons with each other. Polar covalent bonding is a type of chemical bond where a pair of electrons is unequally shared between two atoms.

Question 28

polar molecule (dipole)

Answer 28

a net dipole as a result of the opposing charges (i.e. having partial positive and partial negative charges) from polar bonds arranged asymmetrically. Water (H2O) is an example of a polar molecule since it has a slight positive charge on one side and a slight negative charge on the other.

Question 29

nonpolar molecule

Answer 29

A molecule may be nonpolar either when there is an equal sharing of electrons between the two atoms of a diatomic molecule or because of the symmetrical arrangement of polar bonds in a more complex molecule.

Question 30

cohesion

Answer 30

Ability of water molecules to cling to each other due to hydrogen bonding

Question 31

adhesion

Answer 31

Ability of water molecules to cling to other polar surfaces

Question 32

pH

Answer 32

Mathematical way to indicate the number of hydrogen ions in solution; pH (potential of hydrogen) is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is. More acidic solutions, have lower pH

Question 33

buffer

Answer 33

a compound that accepts H+ in response to a pH change. Theses chemicals or combination of chemicals keeps pH within normal limits; Resists pH change by taking up excess H+ or OH-; pH of blood is about 7.4 – maintained by buffers – the main one is the bicarbonate ion.

Question 34

dissociation

Answer 34

the disconnection or separation of something from something else; Water, which not only dissolves many compounds but also dissolves more substances than any other liquid, is considered the universal solvent. A polar molecule with partially-positive and negative charges, it readily dissolves ions and polar molecules; Due to polarity and H-bonding, water dissolves many substances

Question 35

hydration

Answer 35

a term used to indicate that a substance contains water; When table salt (NaCl) is mixed in water, spheres of hydration form around the ions. Since many biomolecules are either polar or charged, water readily dissolves these hydrophilic compounds.

Question 36

surface tension

Answer 36

the elastic tendency of a fluid surface which makes it acquire the least surface area possible. … At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). Water has a high surface tension - Water molecules at the surface cling more tightly to each other than to the air above mainly due to hydrogen bonding

Question 37

specific heat of water

Answer 37

The specific heat of water is called the calorie (not the same as kilo calories in food), and it is the amount of heat energy needed to raise 1 gram of a substance by 1 degree celsius. Water has a higher specific heat than sand, for example. It takes more heat energy to raise the temperature of water than it does to raise the temperature of sand.

Question 38

heat capacity

Answer 38

The capability of a substance to absorb heat energy; The many hydrogen bonds linking water molecules allow water to absorb heat without greatly changing its temperature.

Question 39

heat of vaporization

Answer 39

the amount of energy (enthalpy) that must be added to a liquid substance, to transform a quantity of that substance into a gas; Takes a great deal of energy to break H bonds for evaporation, heat is dispelled as water evaporates

Question 40

heat of fusion

Answer 40

opposite of heat of vaporization and is the amount of heat energy must withdraw to cause water to freeze or change from liquid to solid.

Question 41

density

Answer 41

the degree of compactness of a substance

Question 42

subatomic particle

Answer 42

the three components of an atom, the proton, neutron, and electron