Unit 6

Question 1

Dobreiner

Answer 1

organized elements into triads

triad- set of three elements with similar properties

Question 2

Newlands

Answer 2

noticed patterns of eight or octaves

arranged elements based on WEIGHT

Question 3

Mendeleev

Answer 3

organized elements based on atomic weight (didn’t know about atomic number)
left blank spaces for elements not yet discovered

Question 4

Mosely - 1913

Answer 4

arranged the periodic table by the number of protons (atomic #)
*modern periodic table, what we use today
invented periodic law

Question 5

periodic law

Answer 5

elements are arranged by increasing atomic number; there is a periodic repetition in their physical and chemical properties

Question 6

periods

Answer 6

horizontal rows in periodic table
7 periods
shows number of the shell or energy level

Question 7

vertical columns

Answer 7

called groups or families
shows the # valence electrons
electrons in the same group have similar chemical and physical properties

Question 8

Group A

Answer 8

known as representative elements

Includes IA-8A

Question 9

Group B

Answer 9

known as transition elements

Includes 1B-8B

Question 10

transition and inner transition generally have __ or ____ valence electrons

Answer 10

1 or 2

Question 11

hydrogen is different because…

Answer 11

it is a nonmetal that acts like a metal

Question 12

metal characteristics

Answer 12

lustrous
malleable
ductile (can be made into wire)
good conductors heat/electricity
form POSITIVE IONS - CATIONS
mostly solid at room temp

Question 13

nonmetal characteristics

Answer 13

dull
brittle
nonconductor (insulators)
some are solid, liquid, or gas
form NEGATIVE IONS - ANIONS

Question 14

metalloids characteristics

Answer 14

semi-metals
characteristics of metals and nonmetals
shiny and brittle
semi conductors

Question 15

Atomic Radius

Answer 15

distance from the center of the nucleus to edge of the electron cloud
*distance from nucleus of one atom to nucleus of other atom divided by two)

Question 16

atomic radius ____________as you go down the vertical columns

Answer 16

increases

Question 17

atomic radius _______ as you go across the periods

Answer 17

decreases

Question 18

effective nuclear charge (explains why atomic radius gets smaller as we move across periodic table)

Answer 18

the effect is that the more positive nucleus has a greater pull on the electron cloud
nucleus is more positive, the electron cloud is more negative
the increased attraction pulls the cloud in making atoms smaller as we move left to right

Question 19

Ionization Energy

Answer 19

energy required to overcome the attraction of the nuclear charge and remove an electron from the atom to form an ion
*easier to remove from a group 1 than group 8
easier to move electrons that are farther away from nucleus

Question 20

Electronegativity

Answer 20

the ability for atoms of an element to attract electrons when they are chemically combined with another element

• Fluorine most electronegative element
• Francium is least electronegative element