Potassium is an exception to the octet rule and can hold up to 12 electrons in its valence electron energy level in a compound.

According to octet rule, the outermost shell of an atom can accommodate maximum 8 electrons (except K shell which can accommodate maximum 2 electrons). Hence, the electronic configuration of potassium is 2,8,8,1 and not 2,8,9.

Potassium (K) atom can lose its outermost shell electron to attain a noble gas configuration.

one electron

gas argon

Magnesium is element 12, so it has 12 protons and a nuclear charge of 12. Moving left to right across a period on the periodic table, each subsequent element has an additional proton and valence electron, but the core electrons which are responsible for the majority of screening remain the same.

Core charge can be calculated by taking the number of protons in the nucleus minus the number of core electrons, also called inner shell electrons, and is always a positive value in neutral atoms. Core charge = 17 − 10 = +7.

The $12 is a common charge added to some car parts by all sellers, and it is called a “Core Charge” as it says on the receipt. It is NOT a walmart added “merchandising fee” as previously stated. When you bring back the old battery, you get the core charge back.

In most states, Walmart will recycle your car battery for you at no charge. You can bring your old battery with you when you purchase a new one to take advantage of this service. Some stores require the original receipt to prove that you purchased the battery at Walmart and paid a core fee.

Where to Sell Used Car Batteries- Getting the Most Money for Your Old Batteries

• Auto parts store. Check with your local auto parts store.
• Scrapyards.
• Metal Recycling Center.
• Craigslist.
• Auto Repair Shops.
• Pawn Shops.
• Newspaper Ads.
• 8. Facebook Marketplace.

The core charge, sometimes called a “core price,” is a deposit you pay until you return your old part. You must pay the core charge when you buy the part. After you replace the pump, you return the old one to the store with your receipt (which includes the core charge).

If you don’t have the core at the time of purchase, you must pay the core charge. That charge is refunded to you when you return the core. A CORE CHARGE IS BASICALLY A RANSOM FOR YOUR OLD PARTS. You will pay a total of $1,400 upfront….How much is a scrap alternator worth?

A core charge is a deposit charged in addition to the price of the replacement caliper that is refunded when you return the old caliper and its hardware to the parts store. OE calipers can cost twice that or more. A typical core charge is about $50.

The core charge, sometimes called a core price, is a form of deposit you pay until returning your old part. You must pay the core charge when you buy the part. After you replace the pump, you return the old one to the store with your receipt (which includes the core charge).

Since a starter is a part that can be rebuilt, it has a core price, in this case, $20. You go home, remove your car’s spent starter, replace it with the new one, and take the old starter back to the auto supply store.

Core charge increases across a period and stays the same down a group as shown in the figure below. Core charge is useful in explaining many of the trends of the Periodic Table.

As we go down a group the distance between the nucleus and valence electrons increases, while the charges involved stay the same. This obviously has the effect of weakening the force of attraction and the valence electron is held with less force.

In general, atomic radius decreases across a period and increases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant. Down a group, the number of energy levels (n) increases, so there is a greater distance between the nucleus and the outermost orbital.

Across a period, effective nuclear charge increases as electron shielding remains constant. This pulls the electron cloud closer to the nucleus, strengthening the nuclear attraction to the outer-most electron, and is more difficult to remove (requires more energy).