Periodic Trends

Question 1

evolution of the periodic table

Answer 1

-daltons first list of elements in 1803 only had 5 elements, hydrogen, oxygen, azote(nitrogen), carbon, and sulfur
-arranged elements by their mass

Question 2

John Dalton (~1810)

Answer 2

-Dalton’s 2nd list had 20 elements published in 1808
-many of his masses were not correct
-he designated a symbol to each number

Question 3

Dmitri Mendelev (~1869)

Answer 3

-he recognizes patterns in the properties of elements and tries to arrange the table by those patterns (by mass)
-anything that repeats is called periodic such as (weather, sleep cycle
-his 1st periodic table was published in 1869
-this method left spaces in the table to be discovered later

Question 4

Henry Moseley (~1911)

Answer 4

-realizes that the patterns correlate with the # of protons
-1st to arrange the table by atomic #
-he discovers the periodic law**
-his table still had holes but they were filled when other elements were discovered

Question 5

Henry Moseley’s periodic law

Answer 5

the physical and chemical properties of the elements are periodic functions of their atomic numbers

Question 6

Modern Periodic Table

Answer 6

-elements are odered by increasing atomic #
-elements with similar properties are in the same group
-each set of elements with similar properties has a name

Question 7

Alkali Metals

Answer 7

group 1
-all end in s for e- configuration
-hydrogen is not one
-extremely reactive because they want to give away their 1 valance electron

Question 8

Alkaline Earth Metals

Answer 8

group 2
-all end in s2 for e- configuration
-2nd most reactive metals
-they are called alkaline because they form a basic solution

Question 9

Transition Metals

Answer 9

groups 3-12
-all have 2 valence electrons from the sublevel
-all elements with e-configuration ending in the d and f blocks
-the metals can take on many different charges
-the f block is often called inner transition metals

Question 10

Lanthanides

Answer 10

1st row on the f-block (starts with lanthanum)

Question 11

Actinides

Answer 11

2nd row of the f-block (starts with actinium)

Question 12

Non-metals

Answer 12

-elements that arent metals
-to the right of the periodic table

Question 13

Semimetals

Answer 13

-also called metalloids
-have properties of both metals and non-metals

Question 14

Halogens

Answer 14

group 17
-have 7 valence electrons
-these are one electron away from having a full sub-level (so they are very reactive non-metals)

Question 15

Noble gases

Answer 15

group 17
-nonreactive because they have a full sublevel
-noble gases have been forced to bond buy the don’t like to

Question 16

Metals (characteristics)

Answer 16

(left side of the stair step line)
-usually solid at room temp and shiny
-malleable and ductile
-good conductors of heat and electricity

Question 17

Non-metals (characteristics)

Answer 17

(right of the stair step line)
-usually gases at room temp
-brittle
-poor conductors of heat and electricty

Question 18

Atomic Radius

Answer 18

size of the atom

Question 19

atomic radius trends

Answer 19

-as you go down each group the radius goes up (higher energy levels are farther from the nucleus making the radius larger)
-as you go from left to right across each row the radius goes down (bc of the increased nucleur charge the e-‘s are stronger pulled towards the nucleus making the radius smaller)

Question 20

Ionic Radius (cations)

Answer 20

cations are smaller than their neutral atoms bc they lose e-‘s. That means the electrons in their valence shell are lost

Question 21

Ionic Radius (anions)

Answer 21

anions are bigger than their neutral atom because they gain electrons. this makes the e- repulsions greater and results in a bigger radius

Question 22

Ionization Energy

Answer 22

-it is the amnt of energy it takes to knock an electron off
–the further out an electron is, the easier it is to steal (so it take less energy to do so
-the larger an atom is the lower its ionization energy
-trend is opposite of the radius trend

Question 23

Ionization Energy trend

Answer 23

-across a row ionization e goes up bc the effective nuclear charge increases
-down a group i.e. goes down bc e-‘s are farther from the nucleus so they aren’t held as tightly and are easier to pull off.

Question 24

Electronegativity

Answer 24

(mine) electronegativity is an element’s tendency to attract a bonding pair of electrons
-how selfish they are with the e-

Question 25

Electronegativity trend

Answer 25

the most electronegative element is fluorine (because noble gases don’t bond)
- the least electronegative is francium
-The trend is like ionization energy but the highest is fluorine not helium

Question 26

order of periodic people

Answer 26

Dalton, Mendeleev, Mosely