CHEMISTRY FOR ENGINEERS MIDTERM EXAMS

Question 1

substances that assume regular, repeating patterns of arrangement of their atoms. substances condense into crystals as solids that fill space as completely as possible.

Answer 1

crystals

Question 2

can be thought of as spheres, and how they fill up a theoretical cubical box called a unit cell.

Answer 2

atoms

Question 3

the seven crystal structures

Answer 3

simple cubic, face-centered cubic, body-centered cubic, hexagonal closed pack, orthorhombic, rhombohedral, tetragonal, and monoclinic

Question 4

made up of atoms at each corner of a cube, and is envisioned as eight spheres on eight corners of a cube. this structure has equal sides, with all the angles of each side as 90.

this is a rare structure and the only elements that occur in this structure are oxygen, fluorine and polonium.

Answer 4

simple cubic

Question 5

crystal system is more common. it is made up of atoms at each corner of a cube with atoms on each “face”

many elements occur as this crystal system in their solid states like aluminum, silver, copper, gold, and nickel. gases in family 8A.

Answer 5

face-centered cubic

Question 6

made up of atoms at each corner of a cube but has an atom at the center.

the alkali metals in group 1A and barium and radium from group IIA are some of the elements

Answer 6

body-centered cubic

Question 7

atoms are piled as layers of hexagons with one atom on each corner and a center atom on the hexagon. the next layer of atoms fill the spaces in between the atoms of the first layer, hence, closed packed.

titanium, zinc, magnesium, and cadmium, including helium and hydrogen gases.

Answer 7

Hexagonal closed packed

Question 8

orthorhombic crystals or rhombic system

Answer 8

consists of three equal angles of 90 degrees. the sides are of different lengths. four types of unit cells, primitive, face-centered, body-centered, and side centered.

sulphur, chlorine, bromine, iodine, protactinium, and neptunium.

Question 9

its axes (a, b, c) are all equal. its corner angles are equal, and all are not perpendicular.

mercury, antimony, and bismuth

Answer 9

rhombohedral or trigonal system

Question 10

three corner angles are perpendicular and two of its sides are of equal length, with the third side either longer or shorter than the other two.

indium and tin

Answer 10

tetragonal

Question 11

three unequal sides comprise it. sides a and c are inclined toward each other at an oblique angle, while the third side b is perpendicular to a and c. two angles are perpendicular while the third angle is not.

curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and lawrencium

Answer 11

monoclinic

Question 12

elements that generally are that are shiny, good conductors of heat and electricity, ductile and malleable. they have the ability to conduct heat and electricity due to the closely packed arrangement of their atoms, making it easier for each atom to transfer with each other.

Answer 12

metals

Question 13

property of metals to be pulled into wires, while malleability is the property of metals to be formed into sheets. it is because of these properties that metals and their alloys can be formed into different shapes such as pipes, tubes, or bars.

Answer 13

ductility

Question 14

the row in a periodic table, elements in the same period are same in size.

Answer 14

period (or series)

Question 15

the column in a periodic table, elements in the same group have the same chemical and electronic properties

Answer 15

group (or family)

Question 16

elements in families IA to 7A.

Answer 16

representative elements

Question 17

these have complete fills s and p subshells

Answer 17

noble elements (group 8A or O)

Question 18

elements in 1B to (B they have filled d orbitals

Answer 18

transition metals

Question 19

elements with no group numbers and have filled f orbitals

Answer 19

inner transition metals.

Question 20

determined by the atomic radius (distance of the valence shell from the nucleus)

Answer 20

atomic size

Question 21

it measures the willingness of an atom to receive electrons, ability of an atom to attract a bonding electron towards itself

Answer 21

electronegativity.

Question 22

an ion with a positive charge. if a neutral atom loses one or more electrons, it becomes this.

Answer 22

cation

Question 23

an ion with a negative charge. if a neutral atom gains one or more electrons, it becomes this

Answer 23

anion

Question 24

is defined as the tensile force per unit area, hence represented by the formula o=F/A

Answer 24

tensile stress

Question 25

refers to change in length per original length, hence represented by the formula e=^L/Lo

Answer 25

tensile strain

Question 26

ratio of stress to strain. it is represented by the formulas:
1) Y=FLo/A^L and
2) Y = o/e

Answer 26

young’s modulus of elasticity

Question 27

refers to the ratio of the change in magnitude of the applied force to the surface area. it is the force per unit area that causes deformation.

Formula: ^P = ^F/A

Answer 27

Bulk stress

Question 28

defined as the ratio of the change in volume, either by compression or expansion, to the original volume. it is the fractional decrease (or increase) in volume.

Formula: e= ^V/ Vo

Answer 28

Bulk strain

Question 29

is defined as the ratio of the applied force per unit area

formula: P= F/A

Answer 29

Pressure

Question 30

refers to the increase in volume of a body due to changes in temperature or decrease in pressure.

Answer 30

expansion

Question 31

refers to the decrease in volume of a body due to compressive force or increase in pressure.

Answer 31

compression.

Question 32

is defined as the resistance of a solid or liquid to a change in volume.

Formulas:
^F/A = -B ^V/Vo
(By substituting ^P)
^P= -B^V/Vo

Answer 32

Bulk Modulus