Honors Chem Unit 6 - Periodic Trends

Stanislao Cannizarro

presented data regarding the determination of relative atomic masses (weights) of various elements

de Chancourtois

arranged the elements along the edge of a cylinder and noticed that chemical properties of the elements were repeating at regular intervals

John Newlands

developed the Law of Octaves

Law of Octaves

the properties of the elements repeated in regular intervals for every 8 elements as atomic mass increased

discovered the periodic table first

Dmitri Mendeleev

how Mendeleev ordered the periodic table

sequentially by atomic weight, then attempted to order elements in vertical columns by shared chemical properties

why Mendeleev left empty spaces on the periodic table

for elements that seemed to be missing from his pattern based on properties

elements Mendeleev left space for on the periodic table not knowing they would later be discovered

gallium and germanium

why Mendeleev placed some elements out of order based on atomic weight on the periodic table

to allow elements to be placed in the correct family based on properties

Henry Moseley

determined the way to approximate the atomic number of an element using emitted X-rays from exciting the electrons of atoms

Moseley’s periodic table

noticed that if atomic number was used rather than atomic weight, the order of the elements on the periodic table would be sequential and follow Mendeleev’s original grouping of families

periods

horizontal rows on the periodic table

groups/families

vertical columns on the periodic table

representative elements

the elements in groups 1-2 and 13-18

transition elements

elements in groups 3-12 and the inner transition elements in the f-block

physical properties of metallic elements

luster, thermal and electrical conductivity, malleability/ductility, high melting points

metallic elements

80% of the elements on the periodic table (the left side of the staircase)

blocks of the periodic table

s, p, d, and f block elements

alkali metals

group 1 of the periodic table

alkali metals qualities

soft and silvery metals, generate hydrogen and violently react when in contact with water

alkaline earth metals

in group 2 of the periodic table

qualities of alkaline earth metals

hard, dense, strong, react slightly with water

hydrogen

group 1 element, explosive gas

helium

group 18, nonreactive

semimetals/metalloids

located in p-block, exhibit properties in between metals and non-metals

examples of metalloids

boron, silicon, germanium, arsenic, antimony, tellurium

halogens

located in the p-block in group 17

characteristics of halogens

nonmetals that are highly reactive

noble gases

located in group 18 in the p-block

characteristics of noble gases

nonreactive gases

transition metals

located from groups 3-12 in the d-block

characteristics of transition metals

metals with low reactivities

lanthanides

in group 3 from atomic number 57-71

lanthanide qualities

rare earth metals

actinides

in group 3, from atomic number 89-103

actinides qualities

radioactive elements made in labs

shape of s orbital

circle

shape of p orbital 

dumbbell 

shape of d orbital

clover leaf

atomic radius

half the distance between two nuclei of the same element

ion

an atom that has lost or gained electrons

positively-charged ions

have more protons than electrons

negatively charged ions

have more electrons than protons

cation

positively charged ion

anion

negatively charged ion

octet rule

almost all ions form and achieve noble gas electron configurations with eight valence electrons

ionic radius

the distance between the nucleus and the outermost shell in an ion

ionization energy

the energy required to excite an electron to the point at which it escapes the pull of the nucleus in the gaseous phase

electron affinity

the change in energy associated with a gaseous atom gaining an electron

electronegativity

tendency of an atom to attract electrons towards itself in a chemical bond with another atom

Coulomb’s Law

the magnitude of the electrostatic force between two charged objects is directly proportional to the magnitude of the charges and the inverse square of the distance between them

subatomic particles that attract

those of opposite types

subatomic particles that repel

those of the same type

periodic trend of ionization energy

increases as you move from left to right across a period

shielding

the repulsion of outer shell electrons from the negative charge of inner core electrons

group trend of ionization energy

decreases as you move from the top to the bottom of a group

periodic trend of electronegativity

increases as you move from left to right across a period

group trend of electronegativity

decreases as you move from the top to the bottom of a group

periodic trend of atomic radius

decreases from left to right across a period

group trend of atomic radius

increases from the top to the bottom of a group

first ionization energy

the energy required to remove one electron from an atom.

size of a cation

smaller than the original atom

size of an anion

larger than the original atom

isoelectronic species

atoms, ions, or molecules that contain exactly the same number of electrons

photoelectron spectroscopy (PES)

an experimental technique to determine the relative energies of electrons in atoms and molecules.

what happens when you move right on the periodic table

The atom gets more protons in the nucleus. But all the new electrons you add go into the same energy level, not deeper shells.

higher effective nuclear charge

a stronger pull from the nucleus as a result of there being more protons

how effective nuclear charge can be approximated

taking the atomic number and subtracting the number of shielding electrons