period trends

Dmitri Mendeleev

Russian chemist who made the first periodic table, organized it by atomic mass

Henry Mosley

updated the periodic table to be organized by atomic number.

Periodic Law

when elements are arranged in order of atomic number, there is a periodic repetition of their chemical and physical properties.

Horizontal Rows

periods

Vertical Columns

groups

where are Metals found

on the left side of the periodic table

where are Non-metals found

on the right side of the periodic table

Metals property

have a high electrical conductivity and luster. They are ductile and malleable

Non-metals propertys

are non-lustrous and poor conductors

Metalloids propertys

show properties of both metals and non-metals and are found on the stair step.

Alkali Metals

Group 1A the most reactive elements

Alkaline Earth Metals

Group 2A

types of

metals include transition metals, inner transition metals, and other metals

Halogens

Group 17 and are the most reactive non-metals

Nobel Gases

the last column of the periodic table, very unreactive because they have a full outer ring of electrons (8 valance electrons)

Electron shielding

the repulsion → like charges repel

electron Siehlding trend

increases down a group and is constant across a period

Atomic Size

the size of an atom

Atomic size trend

increases down a group and right to left across the period

reason for size trend

As you go down a group more energy levels cause the atom to be larger

atom period size trend reason

no energy is added but more protons making the atom smaller

Valence Electrons

the electrons on the outermost shell

Cation

Positivly charged atom

Anion

negatively charged atom

Metals tend to lose elections to get a positive charge

Non-metals tend to gain elections to get a negative charge

Ion Size trend

Same trend as atomic size except anions are always bigger than cations

why are negative ions bigger:

This is because the anions have more electrons than the atom is made from so there will be more repulsion between them causing an increase in the radius

Ionization Energy

the amount of energy it takes to pull an electron from the outside shell of an atom

trend for ionization

Increases up a group increases left to right across a period

reason for trend of ionization

As you go down a group the valence electrons are farther away from the nucleus and so it takes less energy to pull them away from the atom

The more electrons in the outside energy level the less eager an atom will be to lose an electron.

Electronegativity

The electronegativity of an element is the tendency for the atom to attract an electron when combining with other elements.

trend for electronegativty

Increases up a group and increases from left to right across a period

exception for electronegatvity trend

is that noble gasses have an electronegativity of 0 since they already have a full outer shell.

trend for reactivity in metals (in a group)

increase going down

what were elements originally ordered by

atomic mass

trend for reactivity in non metals (in a group

decrease going doown