IB Chemistry SL Topic 3: Periodicity

Periodic table group

The vertical grouping in the periodic table, 1-7 with the last group being 0. Elements in the same group have similar chemical properties. The number of group corresponds to the number of valence electrons

Periodic table periods

The horizontal grouping in the periodic table. Elements in each period have electrons in the same outer shell

Definition of periodicity

the repeating pattern of physical and chemical properties in the periodic table

Transition elements

periods 3-7 have ten transition elements after the first two elements

First ionization energy definition

the energy required to remove one electron from an atom of the element in the gaseous state (kJ mol⁻¹)

First ionization energy trends

Decreases in the group because the valence electrons are farther away from the nucleus.

Increases in the period because more electrons mean more protons and thus a stronger attractive force

Electronegativity definition

an elements relative ability to attract a bonding pair of electrons to itself

Electronegativity trends

Goes down in the group because a smaller atom's nucleus attracts pairs better.

goes up in the period because the greater the number of valence electrons are more desperate to "complete the circle"

electropositive definition

having a low electronegativity

electronegative definition

having a high electronegativity

atomic radii definition

half the distance between two nuclei of bonded atoms

covalent radius definition

the atomic radius of covalently bonded elements

metallic radius definition

the atomic radius of metallically bonded elements

atomic radii trends

Increases down the group because the outer electron is in an energy level progressively further away from the nucleus

Decreases across the period because the more protons means greater attraction on the electrons

atomic radii in positive ions

losing an electron and becoming a positive ion halves the atomic radius as there is more proton-electron attraction

atomic radii in negative ions

gaining an electron and becoming a positive ion doubles the atomic radius as there is less proton-electron attraction and more electron-electron replusion

what happens when a substance melts

the attractive forces holding the particles together are overcome, and the particles are free to move around

how do alkali metals (group 1) react with water?

the react exothermically with water to form hydrogen and ions of the metal hydroxide. Reactivity increases down the period

how do alkali metals (group 1) react with halogens?

React vigorously because alkali easily donate an electron and halogens readily accept electrons. Reactivity increases down the group

What are the four halogen elements?

Flourine, chlorine, bromine, iodine

What does it mean when we say that the halogens are diatomic?

They only exist alone if they are covalently bonded to another atom of themselves

What are the reactive properties of the halogens

They are very reactive, though reactivity decreases down the group. When they react the single bond between the two atoms in the halogen molecule is broken down, then the two atoms each gain an electron to form halide ions

oxidizing ability definition

the ability to accept an electron

amphoteric

can be either acidic or basic

Period 3 trends

the metals form ionic oxides that are basic, and the non metals form covalent oxides that are acidic