Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is...

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Ions Unit 7 Chapter 6

Transcript of Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is...

Page 1: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Ions

Unit 7

Chapter 6

Page 2: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Getting Started

When the difference in electronegativity of two atoms is greater than 1.6,

electrons are transferred from one atom to the other.

Since electrons are negatively charged, when an atom loses an electron,

it becomes positively charged.

Page 3: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Q is the Loneliest Number…

When an atom gains an electron, it becomes negatively charged. You can calculate the charge, Q, by subtracting the number of electrons

from the number of protons: Q = p+ – e-

Aluminum has 13 protons. If it loses 3 electrons, Q = 13 – 10 = +3

Page 4: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Positively Shocking

A cation is a positively charged ion. They form when atoms lose electrons There are more protons than electrons. All metals form cations. Cations have no special name: Na+ is the sodium ion.

Page 5: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Don’t Be So Negative!

An anion is a negatively charged ion. They form when atoms gain electrons There are more electrons than protons. Most nonmetals will form anions.

Page 6: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

The “-ides” of Chemistry

Anions are named by dropping the final syllable(s) of the element

and adding “-ide”. Chlorine becomes chloride, Cl-

Oxygen becomes oxide, O-2

Page 7: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Mono-a-Mono

Monatomic ions are ions made up of single atoms.

For example, magnesium forms the Mg+2 cation

as one single positively charged atom. Bromine forms the Br-1 anion as one single negatively charged atom.

Page 8: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Poly Wanna Covalent Ion!?!

Polyatomic ions are ions made up of more than one atom.

In polyatomic ions, covalent bonds form between atoms within the ion.

The covalent bonds do not dissociate in water.

Electrons have been gained or lost during formation.

Page 9: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

The Cyanide Ion (CN-)

Carbon has 4 valence electrons and N has 5. A covalent bond forms between C and N

sharing 3 electrons each. Carbon steals an extra electron The whole molecule acquires a negative

charge.

CN

-1

Page 10: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Polyelectric…is that like GE?

Polyatomic ions form ionic bonds with other ions.

These ionic bonds will dissociate, and because of this, polyatomic ions

can conduct electricity just like monatomic ions.

Page 11: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Making ‘em Big!

The sulfate ion is SO4-2.

It is made up of one sulfur atom covalently bonded to four oxygen

atoms. When the sulfate ion was formed, it consumed two extra electrons (probably from some metal).

Page 12: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

A Little of this…

The magnesium ion, Mg+2, can combine with the sulfate ion, SO4

-2,

to form magnesium sulfate, MgSO4 also known as Epsom Salts.

Page 13: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

It’s ‘Cause They’re So Cool

When we talked about the Noble Gases, we learned that they are nonreactive

because they have full s and p orbitals (d & f, too).

When the outer s and p orbitals are full, the atom is very stable.

Ions form when atoms attempt to fill their outer s and p orbitals to be

Isoelectronic with the Noble Gases.

Page 14: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

The Yin & Yang of Stabilization

Orbitals are stabilized when they are completely full, completely empty, or half-full (d and f orbitals only).

Since an s-orbital can hold 2 electrons and a p-orbital can hold 6,

atoms are stable when they have 8 electrons in their valence shell

(we usually ignore d’s and f’s).

Page 15: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Eight is Enough

The Octet Rule: Atoms will attempt to gain

or lose electrons to have 8 electrons in their outer s & p

orbitals.

Page 16: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Hangin’ on the p-Block

s- & p-block elements almost always obey this rule,

but d- & f-block elements do not always. d and f-block elements have lots of orbitals

with nearly overlapping energies. Because of this, many elements in the d and

f-blocks can form ions with more than one charge.

Page 17: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Predicting Charges

We can look at the electron configuration of a neutral atom to predict the charge of its ion.

Na = [Ne]3s1 [Ne]3s0 = Na+1

S = [Ne]3s23p4 [Ne]3s23p6 = S-2

Be = [He]2s2 [He]2s0 = Be+2

N = [He]2s22p3 [He]2s22p6 = N-3

Page 18: Ions Unit 7 Chapter 6. Getting Started When the difference in electronegativity of two atoms is greater than 1.6, electrons are transferred from one atom.

Ions

N-3 Na+1 NO3-1 CN-1

B+3 Al+3 ClO4-1 ClO2

-1

Br-1 Sr+2 CO3-2 NH4

+1

O-2 C-4 PO4-3 PO3

-3