Atoms:the foundation of life

Question 1

What keeps the electrons near the nucleus ?

Answer 1

• electromagnetism
• Positive charge of protons attracting negative charge of electrons
• greater distance between them= greater potential energy

Question 2

Define electromagnetism

Answer 2

It is the force that binds negatively charged electrons to positively charged atomic nucle

Question 3

What is Bohr model of electronic structure ?

Answer 3

• electrons in circular orbit nucleus like (planets around sun)
• occupy certain energy levels/shells
• build up electrons in orbits 2,8…(OCTET RULE)

Question 4

Quantum mechanical description of electronic structure ?

Answer 4

-electrons have both particle and wave nature
- electrons have uncertain position and speed
-classical orbits replaced by QM orbitals
-orbitals defined by wave function
-orbitals = diff forms s,p,d,f

Question 5

How many orbitals are there in each shell ?

Answer 5

1 S orbital = 1st shell
1 S &P orbital =2nd shell
1S,P,D orbital = 3rd shell

Question 6

Energies of the orbitals ?

Answer 6

Energies determined by shell number
- sub shells within the same shell have different energies ( S < P < D < F )
- Orbitals within sub shell have diff energies aka DEGENERATE
-energies of n=1,2,3 are separated after this - OVERLAPPING STARTS

Question 7

How many electrons can fit in each orbitals ?

Answer 7

• 2=PAULI PRINICPLE
• each electrons can be spin up or down
• 1 spin up and 1 spin down

Question 8

What is the Pauli principle ?

Answer 8

in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.

Question 9

What is Aufbau principle ?

Answer 9

electrons preferentially occupy the lowest energy orbitals
Build up configuration from the bottom

Question 10

Hunds rule ?

Answer 10

Electrons always enter an empty orbital before they pair up. Electrons are negatively charged- repel each other. Electrons tend to minimise repulsion by occupying their own orbitals.

Question 11

Ionization

Answer 11

Neutral atom is ionised when gaining or losing electrons

Question 12

Ionisation energy

Answer 12

Energy needed to remove an electron from an atom

Question 13

Valence electrons

Answer 13

Electrons with the lowest ionisation energy has the highest energy in the atom

Question 14

Transition metals

Answer 14

Lose their 4s shell before 3d but gain in 4s before 3d