Explanations for atomic trends going across a period (‰)

Explanation According to Coulomb’s Law, the force of attraction between charges is directly proportional to the magnitude of the charges and inversely proportional to the distance between the charges. Since Z eff is increasing across a period, while the distance and the shielding remain constant, there is more attraction between the protons in the nucleus and the outside electrons of elements to the right Trend Definition of Trend Cause of a period - Going across a period, The distance from the center of the atom to Effective Nuclear the valence electrons of the atom decreases Atomic Radius Charge (Z ) increases. - causing those atoms to be more compact . across a period. eff Distance and shielding The size of the atom decreases across a period. remain constant. Electronegativity is the ability of an atom to Going across a period, attract electrons while forming a bond in a Effective Nuclear compound. More electronegative elements - causing those elements to be more Electronegativity Charge (Z ) increases. hold the bond electrons “tighter” or closer to eff electronegative . Distance and shielding themselves. Electronegativity increases across remain constant. a period. Ionization Energy is the amount of energy Going across a period, required to remove one electron from an atom Effective Nuclear Ionization in gaseous state. Higher ionization energy - making it harder to remove electrons from those Charge (Z ) increases. Energy means that it takes more energy to remove one eff elements . Distance and shielding electron from an atom. Ionization energy remain constant. increases across a period. Cations are smaller than their neutral atoms. Going across a period, The radius of cations decreases across a period. Effective Nuclear Anions are larger than their neutral atoms. The Ionic Radius Charge (Z ) increases. - causing those ions to be more compact . radius of anions decreases across a period. eff Distance and shielding In a given period, the anions are larger than the remain constant. cations.

Explanation for atomic trends going down a group (↓)

Explanation According to Coulomb’s Law, the force of attraction between charges is directly proportional to the magnitude of the charges and inversely proportional to the distance between the charges. Since there are more energy levels going down a group, the distance between the protons in the nucleus and the outside electrons increases. For the same reason, there is also more shielding, keeping Z eff constant. These two things combined mean that there is less attraction between the protons in the nucleus and the outside Trend Definition of Trend Cause electrons of elements down a group - The distance from the center of the atom to the Going down a group, valence electrons of the atom increases going distance and shielding Atomic Radius down a group. increase. Effective - causing those atoms to be larger . The size of the atom increases going down a Nuclear Charge (Z eff ) group. remains constant. Electronegativity is the ability of an atom to Going down a group, attract electrons while forming a bond in a distance and shielding compound. More electronegative elements hold Electronegativity increase. Effective - causing those elements to be less electronegative . the bond electrons “tighter” or closer to Nuclear Charge (Z ) themselves. Electronegativity decreases going eff remains constant. down a group. Ionization Energy is the amount of en ergy Going down a group, required to remove one electron from an atom in distance and shielding gaseous state. Higher ionization energy means - making it easier to remove electrons from those Ionization Energy increase. Effective that it takes more energy to remove one electron elements . Nuclear Charge (Z ) from an atom. Ionization energy decreases going eff remains constant. down a group. Going down a group, Cations are smaller than their neutral atoms. distance and shielding Ionic Radius Anions are larger than their neutral atoms. increase. Effective - causing those ions to be less compact . The radius of ions increases going down a group. Nuclear Charge (Z eff ) remains constant.