Atomic structure Flashcards
What is atom?
Atoms are smallest particles of matter
What is an element?
An element is made up of one kind of atom and that cannot be broken down into other substances chemical reactions
Do artificial elements are stable?
No,30 artificial are produced in lab and they are very unstable
What can we know from the columns of periodic table?
Groups of the elements with same properties as well as the valence electrons
What can we know from the rows of periodic table?
Periods(i.e.energy shells)
Sub atomic particles of atom
Atom contains nucleus.Protons and neutrons are inside the nucleus.A cloud of electrons are move around the nucleus.
How subatomic particles are measured?
Atomic mass unit
Charge of subatomic particles
Proton-positive charge (+1)
Neutron-neutral
Electron-negative charge(-1)
What are isotopes?
Atoms of the same element with different numbers of neutrons
Some isotopes are radioactive,what does it means?
Radioactive isotopes contain the nucleus that are unstable and giving out particle and energy when decays.
What is electron shell?
Electrons are arranged in shells around nucleus.
The energy of the 1st shell
Since it is the closest to the nucleus and it has lowest energy level
How electrons are arranged in first 3 shells?
The 1st shell can hold only 2e and it fills first.
The 2nd shell can hold 8e and it fills second.
The 3rd shell can hold 18e but it fills up to 8 and the next 2 go to 4th shell finally the rest are filled to 3rd shell.
288
Why group 0 are unreactive?
B/c they have very stable arrangement of electrons (no valence shell)
Properties of metals
1)Good conductor of heat and electricity
2)high melting point and boiling point i.e.solid at room temperature except mercury
3)hard,strong except Na,K
4)ductile,malleable
5)shiny
6)high density or heavy
7)form positive ions when react
8)react with oxygen to form basic oxides
Properties of nonmetal
1)Poor conductor of heat and electricity
2)low melting point and boiling point i.e.most are gases at room temperature
3)brittle
4)dull
5)low density or heavy
6)form negative ions when react
7)react with oxygen to form acidic oxide
Carbon derivative
Graphite-good conductor
Diamond-very hard and ver high melting point
What is compound?
A substance made by two or more elements with fixed proportions .It has different properties from its elements
What is atomic number(Z)?
The number of protons in the nucleus
What is mass number(A)?
The number of protons + number of neutrons
also known as nucleon number
What is isotopes?
Atoms with the same atomic number but different mass number
What are ions
when atom loses or gains an electron it becomes ions
How positive ions form?
When atom loses electrons it forms a positive ions or cations
How anions can be formed?
When atom gains electrons it forms a negative ions or anions
instrument that used to measure the mass of an atom
Mass spectrometer
Electromagnetic spectrum
Low energy radio waves to high energy gamma waves
What electromagnetic radiation an atom can emit?
Infrared radiation
How absorption spectrum is produced?
When electromagnetic radiation pass through a collection of atoms some of the radiation is absorbed and used to excite the atoms from lower energy to higher level energy
What will happen when atom absorb energy?
an electron moves from lower energy level (ground state) to higher energy level(excited state).
But the excited state is unstable and the electron fall into ground state and giving off energy in the form of electromagnetic radiation (Photon).
The energy released is proportional to frequency of the radiation
Planck equation explanation
The energy of photon is equal to the energy of change in atom
^Eelectron=Ephoton
By Planck eq:Ephoton=hv
^Eelectron=hv
energy level and radiation
n=1,ultraviolet
n=2,visible light
n=3>above,infrared radiation
Electron have _____ properties
wave
What is an atomic orbital?
a region around nucleus in which there is 90% probability of finding the electrons
First energy level
contains one 1s orbital
Lowest energy level
Can hold 2e
2nd energy
Contains one 2s and three 2p orbitals
can hold 10e
Pauli Exclusion
No more than two electrons can occupy any one orbital, and if 2e are in same orbital they must spin in opposite directions
Hund’s rule
If more than one orbital in a sub-level is available,electrons occupy different orbitals with parallel spins
How transition metals lose electrons?
They lose electrons from 4s sub level before 3d sub level
What is ionization energy?
The energy needed to remove one mole of electrons from the ground state of one mole of the gaseous atom
What is the charge if proton and electron?
Charge of proton= +1.67*10^-19C
Charge of electron = -1.67*10^-19C
Which particle has the greatest number of mass?
Proton? Neuton? Electron?
Neutron has the greatest number of charge.
Although the mass of both neutron and proton are approximately 1amu, neutron has slightly heavier mass.