Periodic Table Trends

• going down a group, the number of electron shells increases, which means they are in higher valence shells and have a weaker attraction to the nucleus
• effective nuclear charge is the measure of charge of the valence electrons to the nucleus, and decreases as valence shells fill up due to the repulsion between the inner-shell electrons (aka shielding effect)
• the ENC experienced by valence electrons increases across a period (why...)
• electronegativity is the ability of an atom to attract electrons towards itself. the more strong the ENC of an atom (valence electrons to the nucleus), the greater the electronegativity.
• electronegativity increases across a period
• electronegativity decreases down a period
• atomic radius is the distance from the nucleus to the valence electrons
• atomic radius decreases across a period (valence electrons ENC high)
• atomic radius increases down a group (more valence electrons)
• a positively charged ion is a cation
• a negatively charged ion is an anion
• relative atomic mass (RAM or Ar)is the weighted average of atoms in isotopes, which is calculated using the abundance of said atom.
• to calculate RAM/Ar = ((RIM (mass)*IA (abundance))+ (RIM2*IA2))/100
• mass spectrometry is used to identify an elements relative isotopic mass and abundance, separating the individual isotopes
• the number of peaks in a mass spectrometry graph represents the isotope variations, the horizontal axis is the relative mass of isotopes and the vertical axis is the abundance of each isotope.
• ENC decreases down a group as more outer shell electrons means the e- are held losely
• ionic radius (cation) repulsive forces decreases, so electrons are drawn closer to the nucleus
• ionic radius (anion) gained electron creates repulsive forces to increase
• cation atoms are smaller in ionic radius
• anions are bigger in ionic radius
• Ionisation egergy is the energy required to remove an electron from an atom (1st ionisation energy increases across a period (tight hold of electrons in nucleus) , decreases down a group(electrons not held as close))
• the higher the ENC, the more reactive (halogens and noble gases (non-metals))
• metallic character is a measure of how easily valence electrons are removed (Ionisation energy relation)
• reactivity of metals causes them to lose electrons, the weaker the attraction the more easier it is for electrons to be lost.
• metal reactivity increases down a group
• metal reactivity decreases across a period.
• reactivity of non-metals when they undergo chemical reactions, the more easy it can attract/share electrons, the more reactive
• reactivity of non-metals decreases down a group
• reactivity of non-metals increases across a period
• trends in oxides: go from ionic to covalent across a period, creating a strong base for metals, potentially being amphoteric, or creating strong acidic for non-metals