Atoms and Ions

SNC 2D1

Is drinking too much water bad for you??

Drinking too much water can cause hyponatremia◦Symptoms: disorientation and loss

of balanceExcess water can dilute the

concentration of sodium in the blood to dangerously low levels (with risk of death if untreated)

What?Sodium in the blood??

No! of course not..We are referring to sodium ionsMany ions are necessary for our

health

Example:◦Calcium, phosphorus components

of bone◦Iron help carry oxygen around

body in blood

Atoms vs. IonsAtoms are electrically NEUTRAL

particles with equal numbers of e- and p+

An ion is an atom that has become CHARGED by either gaining or losing electrons in its valence shell

Sodium Atom vs. Sodium IonSodium atoms LOSE one e- when

they react with other atomsThen, each sodium ion contains

11 p+ and only 10 e-Result: sodium ions have an ionic

charge of +1 (a.k.a. Na1+ or Na+)Na contains ONE electron in it’s outer orbit.

Remember…STABLE orbits contain 8 electrons!! So what does this mean?

Fluorine Atom vs. Fluoride Ion

Fluorine atoms GAIN one electrons when they react with other atoms

Therefore, each fluoride ion contains 9 p+ and 10 e-

Result: fluoride ions have an ionic charge of -1 (a.k.a. F1- or F-)F-9

contains 7 electrons in its outer orbit

Remember…STABLE orbits contain 8 electrons!! So what does this mean?

Ions vs. Noble GasesIons are STABLENoble Gases are also

STABLEBecause they have

filled valence shells…

Which noble gas has the same # of e- as Na+?

Which noble gas has the same # of e- as F-?

We say Na+ and F- is isoelectronic to Ne

DID YOU KNOW?Fluoride ions help make tooth enamel

strongFluoride is found in our tap waterFor decades, Canadians have been

getting fewer dental cavities

Try This!!

1)Draw the B-R diagram for an Aluminum atom

2)Draw the B-R diagram for an Aluminum ion

3)Write the new symbol for the Aluminum ion

4)What is the Aluminum ion isoelectronic with? (i.e. what element has the same # of electrons as the aluminum ion?

Aluminum ionAl: 13p+, 13n0, 13e-

Draw the Bohr-Rutherford diagram:

3 valence e-How to reach stability?Gain 5 or lose 3 e-?

What is Al3+ isoelectronic with?Neon!

Try This!!

1)Draw the B-R diagram for a Sulfur atom

2)Draw the B-R diagram for a Sulfide ion

3)Write the new symbol for the Sulfide ion

4)What is the sulfide ion isoelectronic with? (i.e. what element has the same # of electrons as the sulfide ion?

Sulfide ionS: 16p+, 16n0, 16e-

Draw the Bohr-Rutherford diagram:

6 valence e-How to reach stability?Gain 2 or lose 6 e-?

What is S2- isoelectronic with?Argon!

Hydrogen

Unusual elementCan form +ve and –ve ionsAchieves stability by gaining one e-

to fill its orbit (H-) or loses its only e- (H+)

Naming Ions

Cations: positive chargesSame name as the element and

add the word “ion”E.g. Sodium Sodium ion

Anions: negative chargesAdd “-ide” to the stem of the nameE.g. Oxygen oxide ionE.g. Phosphorus phosphide ions