Honors Chemistry - Periodic Trends

Why is it called periodic trends? As in “periodic”?

this refers to anytime something repeats itself on a regular cycle

What did Dobereiner notice?

groups of 3 elements with similar properties and called them “triads”; so he basically found elements similar to each other

What is an example of a triad (according to Dobereiner)?

Calcium, Strontium, Barium —> Sr is an average mass of the two other ones

How many known elements at the time of John Newlands?

62 known elements

How did John Newlands arrange the knot 62 elements?

Arranged in order of increasing mass —> after interval of 8, events of similar physical/chemical properties reappeared

What is The Law of Octaves?

arrange all elements of intervals of 8 — properties reappear

When were Dmitri’s predictions published?

1871

Who invented the modern periodic table?

Dmitri Mendeleev

When did Dmitri publish the modern periodic table?

1869

Dmitri published the periodic table HOW? (published arrangements…)

of known elements classified primarily on chemical properties of these elements; he NOTICED A PERIODICITY OR REGULAR REPETITION OF PROPERTIES WITH INCREASING ATOMIC MASS

What did Dmitri develop in terms of the periodic table (sections)?

8 vertical columns or “gruppe” based on properties such as solubility, electrical conductivity, density, and reactivity

What did Dmitri leave for elements which were unknown at the time (ex. Germanium)?

empty spaces in the periodic table

How are the 2 periodic tables SIMILAR, Dmitri’s and the modern?

Period 2 looks the same as today, group 1 is somewhat similar

How are the 2 periodic tables DIFFERENT, Dmitri’s and the modern?

Copper and Silver are in the wrong group on his table; groups 1 and 10, 2 and 12, etc. but they all have the same valence electrons (so he was very close); NOBLE GASES ARE NOT INCLUDED (this is because they were hard to find back then; 0 reactivity)

Mendeleev’s table has several elements out of sequence based on…

properties

Who discovers the atomic number, WHICH FUNDAMENTALLY DEFINES AN ELEMENT?

Henry Mosely

What does Henry Mosely subject/bombard to discover?

he subjects known elements to x-rays to discover the relationship between atomic number and the x-ray frequency

(Henry Mosely and the subjecting of the known elements to x-rays) The more protons in the nucleus…

the more x-rays will bounce off

We now organize our table based on…

increasing number of protons

In the Modern Periodic Law: The properties of elements are…

periodic functions of their atomic number

Which metal is the MOST metallic?

Francium

Which metal is the LEAST metallic?

Boron

What kind of charges do metals tend to make?

positive

What kind of charges do nonmetals tend to make?

negative

Who invented most of the f block?

Glenn Seaborg

Glenn Seaborg invented specifically…

transuranium elements 94-102 and he places lanthanides/actinides at the BOTTOM

Which has similar properties in terms of elements, periods or groups?

groups

Which group are Alkali metals in and what do they make water?

Group 1, they make water basic

Which group are Alkaline Earth metals in and what do they make water?

Group 2, they make water basic

What group are halogens in and what are they (as in forming)?

Group 17, salt-forming

What group are Noble gases in and what do they not do?

Group 18, they don’t mix with other elements

In terms of specific heat capacity, c, is it high or low in metals?

low c

True/false: Not metals are equally metallic in character.

true, they are not all metallic in character

What are the properties of metals?

electrical conductivity, thermal conductivity, metallic gray/silver luster, solid (high density), malleable/ductile

In terms of metallic character, a periodic trend, how does it increase?

from top to bottom and from right to left across the periodic table

Most metallic elements are found where?

bottom left

Non-metals properties:

poor electrical conductors, good heat insulators, no luster, brittle, solids/liquids/gases

Most non-metals are found where on the periodic table?

top right

Noble Gases are NOT considered….

non-metals

Metalloids are “semiconductors”, a semiconductor…

electrical conductivity falls between conductors and insulators; electricity flows and electricity flows barely (average, in between)

The patterns of the properties of atoms/elements are related to..

atomic numbers; also seems to follow a pattern related to the electron configuration

What are the 4 periodic properties?

Atomic Radius, Ionization Energy, Electron Affinity, Electronegativity

Coulomb’s Law describes..

how electric charges interact with each other—basically, how strongly they push or pull on one another.

More charge =

stronger force
If either charge increases, the force gets bigger.

Farther apart =

weaker force
The force decreases with the square of the distance:

Every trend is going to be described how?

valence electrons attraction and protons; HOW MUCH MORE COULOMBIC ATTRACTION

Variations in these properties of elements depend on the..

electron configurations, especially the configuration in the outermost occupied energy level, and how far away that level is from the nucleus

Effective Nuclear Charge (Zeff)..

the attractive pull experienced by an electron in an atom

In terms of Effective Nuclear Charge, What is Z?

number of protons

In terms of Effective Nuclear Charge, What is S?

the shielding

Will Potassium ONE valence electron feel all 19 protons it has?

no, because of shielding

What are 2 things which effect the Effective Nuclear Charge?

shielding and penetration

The attraction of outer shell electrons for the nucleus is partly counterbalanced by

the repulsion of the outer shell electrons by electrons in the inner shells

Inner shell electrons “shield” the..

valence electrons from the full effect of the nuclear charge

Shielding reduces…

effective nuclear charge