(a) Would you need NaOH or HCl to bring the pH of 0.050 0 M HEPES (Table 8-2) to 7.45? (b) Describe how to prepare 0.250 L of 0.050 0 M HEPES, pH 7.45.
3.10 The Sizes of Atoms (in pm) Shielding • In a many-electronatom, electronsare both attractedto the nucleus and repelledby other electrons. • The cancellingof the nuclear attractiveforceon an electron due to the electron-electron repulsion is calledshielding. Core electrons are the most effectiveat shielding. Effective Nuclear Charge The effective nuclear charge, Z ,eff the net attraction of an electron to a nucleus after screening. Z eff≈ Z – core electrons • Z effincreases from left to right across a row in the periodic table. • Z effreases slightly as you move down a column. Periodic Trends in Properties of Elements Atomic Radius r = ½ d …decreases from left to