Unit 1.3 Flashcards
First ionisation energy def?
the energy required to remove 1 electron from each atom in 1 mole of gaseous atoms
Ionisation of Sodium?
Na(s) —– Na+ + e-
What does removing successive electrons do?
increases the ionisation energy as positive ions are formed
What is the attraction of the positive nucleus dependent on?
shielding
atomic radii
size of the positive charge
Shielding?
all electrons repel each other as they’re negatively charged
electrons in their inner shell repel electrons in their outer shell
This reduces the effect of the positive nuclear charge + more inner shell, the smaller the attractive force and the lower the ionisation energy
Atomic radius def?
the force of attraction between the nucleus and the outer electron decreases as the distance between the, increases and the lower the ionisation energy
What does the size of the positive nuclear charge mean?
the larger the ionisation energy
Shielding effect def?
the repulsion between electrons in different shells
Successive ionisation energies?
a measure of the energy needed to remove each electron in turn until all of the electrons have been removed from the atom
for example?
Sodium
11 electrons so 11 successive ionisation energies
for example the third ionisation energy = a measure of how easily the 2+ ion loses its electron to form a 3+ ion
Na2+(g) —— Na3+(g)+e-
Why do successive ionization energies always increase?
there is always a greater effective nuclear charge as the same number of protons are holding fewer and fewer electrons
As an electron is removed, there is less electron repulsion and each shell is drawn closer to the nucleus
As the atomic radius decreases the nuclear attraction increases
Atomic radius?
the distance between the positive nucleus and the valence electron
Emission and the absorption spectrum
Light takes the form of an electromagnetic wave
visible light is part of the electromagnetic wave
Different types of wavelengths?
radio waves
microwaves
infrared
invisible
ultraviolet
x rays
gamma rays
Radiowave?
has the longest wavelength but lowest frequency
Gamma rays?
highest frequency but shortest wavelength
What is the equation?
C = F LAMDER
C = speed of light (3x10^8m/s)
F = frequency (Hertz)
Lamder = wavelength(m)
Equation for energy?
E = hf
E= energy(J)
h= 6.63 c 10 ^-34 )(Js)
f = hertz
What is energy directly proportional to?
Frequency
what is Energy inversely proportional to?
wavelength
What is the pattern along the waves?
Their wavelengths decrease going from Radiowaves to Gamma rays
Visible length?
Red = 650 - 700 nm
Yellow = 580n
Green = 540 nm
Blue = 480nm
Violet = 400 nm
What is absorption spectra?
light of all visible wavelengths called whitelight
all atoms and molecules absorb light of specific wavelength
when white light is passed through the vapor of an element , certain wavelengths will be absorbed by the atoms + removed from the light
where the wavelength has been absorbed, black lines will appear on a coloured background known as an absorption spectrum
What is an emission spectra?
when atoms are given energy ( by heating ot being placed in an electric field), the electrons are excited from a lower to higher energy level
when the source is removed, the electrons leave their excited state and fall from a higher to lower energy level, releasing a photon of light
the photon of a light has a specific wavelength and frequency
Emission spectrum = coloured lines on black background
