UNIT 1 CHEM

quantum mechcanics of an electron

can be extremely small, electron can be both a particle and a wave

standing wave

mode of vibration formed by the superposition of two waves in opposite directions, creating fixed nodes and antinodes.

position of the electron

we somewhat k ow the position from the Bohr Rutherford model however we cannot know the area and speed of the electron because its far too small

orbital

a probable area where we can predict where the electron is. each shell has sub shells each sub shell have an orbital and each orbital can have two electrons

orbital vs orbit

distance varies from neucleues vs nucleus is fixed

aufbau princpial

electrons will fill lowest to highest energy orbitals

pauliexclusion principal

no two electrons can spin the same way

hunds

all electrons must be unpaired before a second one appears

anion

negatively charged

more electrons present

cations

positively charged

less electrons

ionic bonds

metal +non metal

cation +anion

has a crystal lattice structure - cation is surrounded by anions

ionic bond properties

good conductors

high melting and boiling points

soluble in water

Covalent bonds

non metal x2

equal sharing of electrons = non polar

unequal sharing of electrons = polar

valence bond theory

electrons are in orbitals in specific shape and location

sharing electrons means overlapping valence orbitals

which forms a new orbital shape that houses both electrons

polarity

when electrons are shared they will either be equally or unequally shared favouring one element more than the other making one side more negative

electronegtaivitiy

the ability or strength to keep or take electrons

the higher the en the better it van take electrons away

smaller atoms and non metals have higher en

non polar polor and ionic en

np 0-0.4

0.4-1.7

1.7+

which elements don’t follow the octet rule

h b be n

sigma bond

overlap of two s orbitals

pi bond

overlap of two p orbitals - if not all p bonds get hybridized it will stick out of the orbital like a plane

What did Rutherford propose about electron movement in atoms?

Electrons orbit in a circle around the nucleus.

What happens to an electron that is constantly orbiting the nucleus according to physics?

It emits photons, losing energy and risking a crash into the nucleus.

How is light emission measured?

Light emission is measured in waves.

How does wavelength relate to energy?

The shorter the wavelength, the higher the energy emitted.

What device measures how much energy is emitted by elements?

Spectrometer.

What occurs when an element is burned in terms of energy?

It breaks its bonds, absorbs energy, and eventually releases it in wavelengths.

What are energy levels in atoms represented by?

They are represented as n one, n two, n three, etc.

What happens when energy is absorbed by electrons?

Electrons rise to higher energy levels.

What is the behavior of electrons when they release absorbed energy?

They emit light as they fall back to their original energy level.

What does Bohr's model explain about hydrogen?

It describes the relationship between electrons, energy levels, and the spectrum of hydrogen.

What is a limitation of Bohr's model?

It only works well for hydrogen and does not apply effectively to multi-electron atoms.

heisgingebergs uncertainity principal

we don’t know exact place or speed of an electron