{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

LECTURE 09 Metallic bonding

LECTURE 09 Metallic bonding - SUMMARY FROM LAST CLASS...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Dr. P. Lucas U of A MSE 110 Covalent Bonding SUMMARY FROM LAST CLASS Atoms with similar electronegativity form covalent bonds by combining and sharing two electrons into a molecular orbital delocalized over the two atomic nucleus. The σ bonding MO made by addition of two AO has low energy and contribute towards the covalent bond. σ = 1 s A + 1 s B The σ * antibonding MO made by subtraction of two AO has high energy and contributes against the bond. σ * = 1 s A - 1 s B The bond order is define as BO=½(e - in σ e - in σ * ) and represent the number of covalent bonds between two atoms. The interaction of two p z AO generates σ and σ * MOs, while p x and p y generates π and π * MOs. O 2 has two unpaired electrons and is paramagnetic while N 2 has no unpaired electrons and is diamagnetic . Covalent bonds are very directional and have high bond strength, hence covalent solids formed from 3-D covalent network generate very hard materials such as diamond.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Dr. P. Lucas U of A MSE 110 Metallic Elements: BONDING IN METALS All the pure elements from the left of the periodic table are metals while the rest are covalent. Metals are electrical conductors while metalloids are semiconductors and nonmetals are insulators.
Image of page 2
Dr. P. Lucas U of A MSE 110 Metallic bonds A simple model for metallic bonding is the free electron gas model . BONDING IN METALS Na [1s 2 2s 2 2p 6 3s 1 ] Æ Na + [1s 2 2s 2 2p 6 3s 0 ] + e - In this model the valence electrons form a “sea” or gas of free electrons around the metal cations cores (Na + ) . Hence, one of the most defining characteristics of metals is their high electrical conductivity .
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern