Periodicity Flashcards
Atomic radis
Distance from nucleus to outermost electron
Ionic radius
Distance from nucleus to outermost electrons in an ion
Electron affinity
Energy released when one mole of an electron is added to one mole of gaseous atoms. Shown by X (g) —> X+ (g) + e-
Electronegativity
A measure of the attraction an atom has for a shared pair of electrons in a covalent bond
Periodicity
Repeating trends or patterns of physical/chemical properties in elements
Trend and explanation: Atomic Radius down a group
AR increases down a group as the number of electron shells increases
Trend and explanation: Atomic Radius across a period
AR decreases left to right across a period because the nuclear charge increases with each added proton
Trend and explanation: Ionic Radius for positive ions
IR decreases across a period because positive ions increase left to right in number of protons but decrease left to right in number of electrons; greater attractive force=smaller radius
Trend and explanation: Ionic Radius for negative ions
IR decreases across a period as the number of protons increases but the number of electrons stays the same
Trend and explanation: Ionization Energy
IE increases across a period and decreases down a group. Higher charge/attraction=harder to remove electrons across a period, lower attraction down a group=easier to remove.
Trend and explanation: Electron affinity (including metals vs. nonmetals)
Metals=low EA, non metals=higher EA. Greater distance between nucleus and outer energy level=weaker attraction, less energy released when an electron is added
Trend and Explanation: Electronegativity
Increase across a period, decrease down a group. Metals have low EN, nonmetals have high EN (gain electrons more easily)
What is the general trend for melting point?
Increases across a period until group 14, then decreases (depends on bond type, structure, and strength of metallic bond)
metallic character is…
how easily an atom can lose electrons
Metalic character___down a group and ___across a period
Increases down a group, decreases across a period.
Trends and explanation: atomic/ionic radius for group 1 (alkali metals)
Increases down a group; more energy levels.
Trend for First IE for alkali metals
Decreases down a group as valence e- are further from nucleus
Trend for electronegativity for alkali metals
Decreases down a group because of shielding/distance
Trend for melting point for alkali metals
Decrease down a group as atoms become larger; therefore metallic bonds become weaker.
Trend for reactivity for alkali metals
increases down a group as the valence electron becomes easier to lose
What trends for halogens are the same as alkali metals?
AR/IR, first IE, EN.
What two trends are different for halogens than alkali metals?
Melting points and reactivity
Trend for halogens for melting point
increases down a group as Van Der Waal forces become greater with more electrons
Trend for halogens for reactivity
Decreases down the group as attractive force between nucleus and valence e- decreases
Properties of metals in period 3 (6)
Shiny, good conductors, ductile, malleable, reducing agents (form cations), metal oxides act basic and neutralize acids.
Properties of halogens in period 3
Non-metals=solid, liquid, or gas. Oxidizing agents, form anions. Oxides are acidic.
What is special about aluminum oxide?
It is insoluble in water and amphoteric (can be acid or base)