Protons and Electrons A proton carries a positive charge (+) and an electron carries a negative charge (-), so the atoms of elements are neutral, all the positive charges canceling out all the negative charges. Atoms differ from one another in the number of protons, neutrons and electrons they contain.

An ion is a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule. An atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

An anion (pronounced “anyin” (−) (/ˈænˌaɪ.ən/), from the Greek word ἄνω (ánō), meaning “up”,) is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged).

Slide 2: What happens when two negatively charged ions get close to each other? The two negatively charged ions repel each other.

A strong acid like HCl donates its proton so readily that there is essentially no tendency for the conjugate base Cl– to reaccept a proton. Consequently, Cl– is a very weak base. A strong base like the H– ion accepts a proton and holds it so firmly that there is no tendency for the conjugate acid H2 to donate a proton.

There is a relationship between the strength of an acid (or base) and the strength of its conjugate base (or conjugate acid): ⚛ The stronger the acid, the weaker its conjugate base. ⚛ The weaker the acid, the stronger its conjugate base. ⚛ The stronger the base, the weaker its conjugate acid.

Strong acids have a weak conjugate base. HCl can only be a good proton donor, however, if the Cl- ion is a poor proton acceptor. Thus, the Cl- ion must be a weak base.

A strong base is a base that is completely dissociated in an aqueous solution. These compounds ionize in water to yield one or more hydroxide ion (OH-) per molecule of base. In contrast, a weak base only partially dissociates into its ions in water. Strong bases react with strong acids to form stable compounds.

Bases have these characteristics:

• Bitter taste (opposed to sour taste of acids)
• Slimy, or soapy feel on fingers (Slippery)
• Many bases react with acids and precipitate salts.
• Strong bases may react violently with acids.
• Bases turn red litmus paper blue.
• Bases are substances that contain metal oxides or hydroxides.

There are 7 strong acids: chloric acid, hydrobromic acid, hydrochloric acid, hydroiodic acid, nitric acid, perchloric acid, and sulfuric acid. Being part of the list of strong acids doesn’t give any indication of how dangerous or damaging an acid is though.

Strong Arrhenius Bases

• Potassium hydroxide (KOH)
• Sodium hydroxide (NaOH)
• Barium hydroxide (Ba(OH)2)
• Caesium hydroxide (CsOH)
• Sodium hydroxide (NaOH)
• Strontium hydroxide (Sr(OH)2)
• Calcium hydroxide (Ca(OH)2)
• Lithium hydroxide (LiOH)

NH4OH, being a weak base, ionizes to a less extent while NH4Cl being a strong electrolyte ionizes almost completely. When a small amount of strong acid like HCl is added, the H+ ions combines with OH- to form un-dissociated water molecules. However, to maintain Ka constant, NH4OH dissociates more thus removing H+ ions.

Classifying Electrolytes

Answer: Ba(OH)2 dissociates OH- which can absorb H+. That’s why Ba(OH)2 is a base. In aqueous solution, anything donates OH- is considered to be a base.