TEST #1: Chapter 1

Question 1

How to find the number of neutrons?

Answer 1

subtract the atomic number from the mass number

Question 2

What does the A, X, & Z stand for in isotopic symbols

Answer 2

A= mass number
X = element symbol
Z= atomic number

Question 3

The # of protons in an atom equals…?

Answer 3

its atomic number

Question 4

What are isotopes?

Answer 4

atoms with the same number of protons but different number of neutrons

Question 5

What is an element’s mass number?

Answer 5

the number of protons + the number of neutrons

Question 6

What are the two ways of symbolizing isotopes?

(ignore the apostrophes)

Answer 6

1. A
   ``X
   Z

OR

2. X- A

Question 7

( X-A example) If X is Fluorine and its mass # is 20, then what would the isotopic symbol be?

Answer 7

Fluorine - 20

Question 8

If X is Hydrogen and its mass # is 2, what would the isotopic symbol be?

Answer 8

2
``H
1

Question 9

What’s the electron cloud?

Answer 9

• space in which electrons are likely found
  ~ electrons with the LOWEST energy are found in the energy level CLOSEST to the nucleus
  ~ electrons with the HIGHEST energy are found in the OUTERMOST energy levels (FARTHER from the nucleus)

Question 10

What’s the wave model?

Answer 10

• according to the theory of wave mechanics, electrons DO NOT move about an atom in a DEFINITE PATH
• it is impossible to determine the exact location of an electron - the probable location of an electron is based on how much energy the electron has
• according to the modern atomic model, an atom has a small positively charged nucleus surrounded by a large region in which there are enough electrons to make an atom neutral

Question 11

What are valence electrons

Answer 11

outer electrons

Question 12

What are the families on the periodic table

Answer 12

group 1 - alkali metals
group 2 - alkaline earth metals
Groups 3-12 - transition metals
group 17 - halogens
group 18 - noble gases

Question 13

How are elements in the same family similar?

Answer 13

they have the same number of valence electrons

Question 14

What’s atomic radius?

Answer 14

distance from the nucleus to the valence shell of a neutral atom
~measured in picometers (pm)

Question 15

What’s ionization energy?

Answer 15

the energy needed to completely remove an electron from a gaseous atom or ion

Question 16

What’s the first ionization energy?

Answer 16

the energy required to remove the first valence electron from a neutral atom

Question 17

What’s the second ionization energy?

Answer 17

the energy required to remove a second electron from the univalent ion to form the divalent ion

Question 18

What happens to ionization energy as you move left to right across a period on the periodic table?

Answer 18

ionization energy increases

Question 19

What happens to ionization energy moving down a group on the periodic table?

Answer 19

ionization energy decreases

Question 20

What happens to atomic radius as you move across a period from left to right?

Answer 20

it decreases

Question 21

What happens to atomic radius as you move down a given group?

Answer 21

it increases

Question 22

What’s electron affinity?

Answer 22

the energy absorbed or released when an electron is added to a neutral atom

Question 23

What’s electronegativity

Answer 23

a measure of the attraction of an atom for the electrons in a chemical bond
~ an indicator of the relative ability of an atom to attract shared electrons

Question 24

What’s the shielding effect

Answer 24

the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell

Question 25

Why does the atomic radius decrease across a period from left to right?

Answer 25

• atomic radius decreases as electrons are added one at a time to the outer energy shell
  ~ electrons in a shell cant shield each other from the attraction to the protons; as the number of protons increases, the effective nuclear charge also increases across a period

-> due to the increasing nuclear charges

Question 26

why does the atomic radius increase down a given group

Answer 26

• as you move down a group, the number of electrons and filled electron shells increase but the # of VALENCE ELECTRONS remains the same
  ~ As the number of filled energy shells increases, the electrons are found farther from the nucleus causing the atomic radius to increase

-> due to the increasing number of electron shells

Question 27

As you move left to right on the periodic table, what happens?

Answer 27

• atomic radius decreases
• ionization energy increases
• electronegativity increases

Question 28

As you move down a given group, what happens?

Answer 28

• atomic radius increases
• ionization energy decreases
• electronegativity decreases