Atomic Structure: Electronegativity

Hello everyone, this is Nelsa blogging for Friday's class! This time, I'm going to save after every sentence. I am not going to go through losing everything again.

Soo, let's get to the point.


I. ELECTRONEGATIVITY

electronegativity: Indicates the relative ability of its atoms to attract electrons in a chemical bond.

Basically, as you move across the periodic table - from left to right - electronegativity increases, and as you move down the periodic table, electronegativity decreses.

In grade nine (.. or last year), we were told that a bond between a metal and a non-metal is ionic, and a bond between two non-metals is covalent. That's still true for the most part, but on Friday, we found out why that's true. Chemical bonds between different atoms are never completely ionic or covalent, and what type of bond it is depends on how strongly the bonded atoms attract electrons.

We'll need the electronegativity difference to figure out the character of the bond. Having a difference of 1.70 is considered 50% covalent and 50% ionic. A number that's greater than 1.70 is then considered ionic and a number that's less than 1.70 is then considered covalent.



II. IONIZATION ENERGY

ionization energy: The energy required to remove an electron from a gaseous atom.

An atom with a high ionization energy value has a strong hold on its electrons, which means they are less likely to form positive ions. The opposite is true for atoms with a low ionization energy value.

When you move across the periodic table - left to right - the ionization energy increases, and when you move down the table, the energy decreases.



III. ATOMIC RADIUS

The electron cloud surrounding a nucleus doesn't have a clear edge, therefore the atomic radii can't be measure directly.

atomic size: How closely an atom lies to a neighbouring atom.

For metals, the atomic radius is half the distance between adjacent nuclei in an element [d/2], and for elements that occur as molecules, the radius is half the distance between nuclei of identical atoms that are chemically bonded together.

As you move across the periodic table - left to right - the atomic radii decreases, and it increases as you move down a group.



IV. IONIC RADIUS

When atoms lose electrons and form positively charged ions, they become smaller. When atoms gain electrons and form negatively charged ions, they become larger.

Moving across the periodic table - left to right - will decrease the size of positively charged ions, and increase the size of negatively charged ions. The ionic radii of both positive and negative ions increase as you move down the table.


That's basically a summary of what was on those sheets that (you should) have gotten on Friday. Mm, we were given two worksheets for homework, and one that we did in class together.

Yeah.. that's it! I hope you guys had a good weekend. Happy Monday! xD

Next scribe will be ALVINA.