atoms, ions and molecules

Question 1

what is the chemists’ view of an atom?

Answer 1

all matter is made up of atoms, and atoms are made up of the subatomic particles: electrons, protons, and neutrons

Question 2

what is a proton?

Answer 2

determines the identity (element) of the atom

Question 3

what is an electron?

Answer 3

determines the relative electric charge of the atom

Question 4

what was the first subatomic particle discovered?

Answer 4

the electron

Question 5

What experiment did J.J. Thomson perform and what did he conclude from it?

Answer 5

-he used an apparatus known as a cathode ray tube and found that the phosphorous gas in the tube excites electrons when a current passes through. A green light would appear where electrons were. The light would move when exposed to a magnet.
-discovered that the particles that make up the cathode ray are charged and are a part of all matter. Identified the existence of electrons

Question 6

what experiment did Robert Millikan perform and what did he conclude?

Answer 6

-used an apparatus in which an X-ray beam ionized N2 and O2 by making them lose electrons. As the oil drops passed through the beam, they picked up electrons. Between the positive and negative plate, the drops start to fall because of gravity then stop because of an attraction to the positive plate
-discovered that there is an exact charge for electrons

Question 7

what was the model of the atom created by J.J. Thomson?

Answer 7

-the plum pudding model
-proposed that the electrons were distributed evenly through a homogenous sphere of positive charge

Question 8

What was Ernest Rutherford’s experiment and what did he conclude?

Answer 8

-radioactive alpha particles were created from aluminum and shot at a gold foil. Majority of the particles traveled through the foil, but some particles were scattered
-concluded that there is a small, centralized nucleus in an atom that is positively charged

Question 9

what would’ve happened in Rutherford’s model if the plum pudding model was true? Why did he come to the conclusion he did based on the experiment?

Answer 9

-if the plum pudding model was correct, the alpha particles would push through the gold foil
-the alpha particles that scattered did so because of the condensed nucleus containing protons

Question 10

what is the location, symbol, relative charge, and relative mass of an electron?

Answer 10

-outside the nucleus
-e-
- -1
- 1/1836

Question 11

what is the location, symbol, relative charge, and relative mass of a proton?

Answer 11

-inside the nucleus
- p+
- +1
- 1

Question 12

what is the location, symbol, relative charge, and relative mass of a neutron?

Answer 12

-inside the nucleus
- n0
-0
- 1

Question 13

what is an isotope?

Answer 13

atoms of the same element with varying number of neutrons in the nucleus

Question 14

what is an atomic number?

Answer 14

each element has a characteristic number of protons in the nucleus

Question 15

what is the atomic mass number?

Answer 15

total number of protons and neutrons in he nucleus

Question 16

what is nuclide notation?

Answer 16

used to display the number of protons and neutrons in the nucleus

Question 17

in nuclide notation, where are the mass number, atomic number, and number of electrons located?

Answer 17

-mass number- top left of the element
-atomic number- bottom left of the element
-number of electrons- top right of the element

Question 18

what is the periodic table?

Answer 18

a tabular arrangement of elements in rows and columns, highlighting the regular repetition of properties of the elements

Question 19

what is a period on the periodic table?

Answer 19

the elements in one horizontal row

Question 20

what is a group (family) on the periodic table?

Answer 20

the elements in one vertical column. These elements have the most similarities between elements and how they react

Question 21

where are the nonmetals located on the periodic table?

Answer 21

-H in period 1 group 1
-elements above the staircase from group 14-18

Question 22

where are the metalloids located on the periodic table?

Answer 22

-on the staircase in groups 13-16

Question 23

where are the transition metals located on the periodic table?

Answer 23

-from group 3-12

Question 24

where are the main group metals found on the periodic table?

Answer 24

-group 1 and 2
-below the staircase in groups 13-16

Question 25

what are metals? Name all characteristics.

Answer 25

-solids with high melting points and high densities and have bright, metallic luster -good conductors of heat and electricity -malleable- can be hammered into thin sheets -ductile- can be drawn into fine wires -majority of elements -form cations with positive charges (loses electrons)

Question 26

what are nonmetals? Name all characteristics.

Answer 26

-typically have low melting points and low densities and have a dull appearance -poor conductors of heat and electricity -not malleable or ductile and crush into a powder when hammered -eleven nonmetals occur naturally in the gaseous state -form anions with negative charges (gains electrons)

Question 27

what are the characteristics of metalloids?

Answer 27

have properties midway between those of metals and nonmetals

Question 28

where are the noble gases located on the periodic table?

Answer 28

group 18

Question 29

where are the halogens located on the periodic table?

Answer 29

group 17

Question 30

where are alkaline earth metals located on the periodic table?

Answer 30

group 2

Question 31

where are alkali metals located on the periodic table?

Answer 31

group 1 minus H+

Question 32

which nonmetals occur naturally as diatoms (7)?

Answer 32

-Hydrogen (H2) -Nitrogen (N2) -Oxygen (O2) -Fluorine (F2) -Chlorine (Cl2) -Bromine (Br2) -Iodine (I2)

Question 33

what is an atomic mass unit (amu)?

Answer 33

a unit used to express the relative masses of atoms and subatomic particles

Question 34

what is the equation for a weighted average?

Answer 34

(mass)(abundance) + (mass)(abundance) = average mass

Question 35

what is the atomic mass of copper if 63-Cu has atomic mass of 62.930 amu and 69.09% abundance and 65-Cu has a mass of 64.928 amu and an abundance of 30.91%?

Answer 35

63.55 amu - (62.930)(0.6909) + (64.928)(0.3091)

Question 36

what is a mole?

Answer 36

a unit for a specific number; convenient unit for expressing microscopic quantities involved in macroscopic processes we observe. It is the smallest unit we can see of atoms or molecules

Question 37

what is Avogadro's number (1 mole)

Answer 37

6.022 x 10^23

Question 38

what is the molar mass?

Answer 38

the mass (in grams) equal to the mass of an individual atom or molecule (amu)

Question 39

what is a molecular mass?

Answer 39

mass of one molecule of a molecular compound; it can be found with the sum of the atomic masses of the atoms in that compound

Question 40

what is a formula mass?

Answer 40

mass in atomic mass units of one formula unit of an ionic compound

Question 41

if given the mass of an element, what steps would you take to find the moles of the element?

Answer 41

divide by the molar mass

Question 42

if given the mass of an element, what steps would you take to find the atoms of the element?

Answer 42

1. divide by the molar mass 2. multiply by Avogadro's number

Question 43

if given the compound H2O, what steps would you take to find the mass of the element H

Answer 43

1. divide by Avogadro's number 2. use the chemical formula 3. multiply by the molar mass

Question 44

In Rutherford's gold-foil experiment, only a small fraction of alpha particles were reflected back towards the alpha source. As a result, what can we conclude about the atom?

Answer 44

only a small region of the atom has a positive charge

Question 45

Thomson obtained the value of -1.759 x 10^11 C/kg (Coulombs/kilogram) for the charge-to-mass (e/m) ratio for the electron. Millikan determined the charge (e) on the electron to be -1.602 x 10^-19 C. What is the mass of the electron?

Answer 45

9.107 x 10^-31 kg - (1 kg/-1.759 X 10^11 C) x -1.602 x 10^-19 C

Question 46

Two stable isotopes of an element have isotopic masses of 10.0129 amu and 11.0093 amu. The atomic mass is 10.81. Which isotope is more abundant?

Answer 46

The isotope with a mass of 11.0093 is more abundant

Question 47

Calculate the mass, in grams, of 10 copper atoms

Answer 47

1.055 x 10^-21 g -(10 atoms/ 6.022 x 10^23)= 1.661 x 10^-23 -1.661 x 10^-23 x 63.55 (molar mass) =

Question 48

what is the group number of titanium?

Answer 48

4

Question 49

what is the period number of sodium?

Answer 49

3

Question 50

how many atoms are in 4.35 x 10^3 moles?

Answer 50

2.62 x 10^27

Question 51

this type of element is malleable, ductile, has high melting and boiling points, and form cations

Answer 51

metals

Question 52

this type of element is not malleable or ductile, has low melting and boiling points and form anions

Answer 52

non-metals

Question 53

what family does fluorine belong to?

Answer 53

halogens

Question 54

which of the following is not a diatomic element: Hydrogen, bromine, chlorine, or carbon

Answer 54

carbon

Question 55

who determined the charge of an electron and what did he use?

Answer 55

-JJ Thompson -cathode ray tube

Question 56

who determined the charge of an electron?

Answer 56

Robert Millikan

Question 57

Who proposed a subatomic model (plum pudding model) of the atom?

Answer 57

JJ Thomson

Question 58

who found out that there is a nucleus in the atom separating + and - charge?

Answer 58

Rutherford

Question 59

a metal sample is hammered into a rectangular sheet with an area of 31.2 ft^2 and an average thickness of 2.30 x 10^-6 cm. If the mass of this sample is 0.4767 g, predict the identity of the metal. (1 in = 2.54 cm) a. aluminum (2.70 g/cm^3) b. copper (8.95 g/cm^3) c. gold (19.3 g/cm^3) d. zinc (7.15 g/cm^3)

Answer 59

d. zinc (7.15 g/cm^3)

Question 60

which statement is not true concerning cathode rays? 1. they originate from the negative electrode in a cathode ray tube 2. they travel in straight lines in the absence of electric or magnetic fields 3. they are made up of electrons 4. the properties of cathode rays are dependent on the cathode material

Answer 60

4. the properties of cathode rays are dependent on the cathode material

Question 61

the ion X2+ has 24 electrons. What is a possible identity for X?

Answer 61

Fe

Question 62

which of the following is a correct statement: a. tin is a transition element b. lead is a nonmetal c. antimony is a metalloid d. elements are arranged in order of increasing atomic mass

Answer 62

c. antimony is a metalloid

Question 63

what is the relationship between frequency and wavelength?

Answer 63

frequency is inversely proportional to wavelength