Matter,atom and Periodic table Flashcards
What is matter
Matter is any substance that has mass and takes up space by having volume
What are 3 physical states of matter
Solid-rigid form of matter;definite shape and occupies fixed volume(at a particular T and p)
Liquid-fluid form of matter;occupies fixed volume(at part.T and p) but doesnt have fixed shape. It has well defined horizontal surface and takes shape of the container
Gas-fluid form of matter. It spreads out to fill the space containing it and takes up the shape of the container
What are condensed forms of matter
Liquids and solids
What are fluids
They have enough energy to overcome the forces between molecules and move past one another so that the substance flows.
What is vapour
It is often used for the gaseous state of a substance that is normally a solid or a liquid at room temperature
Types of transformation of matter
Physical transformation-no variation in chemical composition
Chemical transformation-variation of chemical composition
What is energy
Capacity to do work. Work is done when motion occurs against force
What is Dalton’s theory
- All matter has discontinuous nature and is composed of atoms
- In a specific elements all atoms are identical( mass dimension properties)
- Compound consists of 2/more atoms of diff elements and the atoms are alwqys present in the same ratio
- Overall mass of products must be equal to the one of the reactants
What is Thomson’s model
Atom is a sphere of + charge with electrons present inside the sphere. += - charge=>neutral
Rutherford’s model of an atom
Planetary model, he majority of mass is in nucleus(p+ and n0). Electrons revolve around nucleus in a fixed path(orbits). A volume occupied by the nucleus is very small compared to the volume occupied by the atom
Atomic number
Number of protons(Z)-subscript on the left side
Atomic mass number
A= Z+N(number of neutrons)-superscript on the left
What are isotopes
Atoms of the same element that have different number of neutrons in their nuclei
What are hydrogen isotopes
Protium(H1-no neutrons), Deuterium(H2-1n⁰) Tritium(H3-2n⁰)
What is stable isotope
When it’s not radio active
Radioisotopes
Unstable form of the element that emit radiation to transform into a more stable form
What are alpha and beta particles and gamma rays
•Alpha particles- 2p+ and 2n⁰->heaviest type of radiation particle. Very low penetration
•Beta particles-e- that are not attached to an atom. Small mass and a negative charge. Low penetration
•Gamma rays-electromagnetic radiation. No mass or charge. High penetration
What are drawbacks of Rutherford’s model
It failed to explain the stability of atom. It didnt follow laws of classical physics
Are atoms stable
Yes and they emit only definite wavelengths
What is electromagnetic radiation
It is a form of energy consisting of oscillating electric and magnetic fields. Those oscillation travel through space at a speed of light. These types of EM radiation each have a characteristic wavelength
c=y(naopacke)v(frequency)
What is spectroscopy
Atoms can absorb or emmit EM radiotation and the spectroscopy studies this absorptions or emmisions
What is EM spectar
Radio waves, microwaves, infrared, visible light(740nm-390nm), ultraviolet, x-rays , y-rays
What are photons
Packets of quanta of radiation that are emmited or absorbed
What is energy of the photon proportional to
To its frequency
E=hv
H=>planks constant
What is atomic and continuous spectrum
In a continuous spectrum all frequencies are emmited while in atomic spectrum only discrete frequencies are emmited(the spectrum is different for each element)
Bohr’s model
E- moves in a fixed orbit(like a planet around the sun). Energy associated with each orbit have a fixed value and electron can move from one orbut to another by emmiting or absorbing energy. E- can not lie between orbits
L. De Broglie; wave particle duality
In some instances they act as waves and in some as particles. Wavelength is inversely proportional to the mss and the velocity of the matter
Y(flipped)=h/mu(velocity)
e- keep their energy and do not collapse because they behave as waves
The Heisenberg uncertainty principle
We can not know e- certain position so we need to consider probabilities of the electrons being in certain volumes of space
It is not appropriate to imagine an electron in a definite orbit
Schrodinger equation
Introduces:
•particle nature in terms of mass
•wave nature in terms of wavefunction ш which varies with position
Ш² is proportional to probability of finding e- withing a small volume of space
What is electron density
Probability per unit volume
Atomic orbital
Eegion of space around the nucleus where there is a highest pribability of finding the e-
What are atomic orbitals characterized by
3 quantum numbers: n l ml
e- is characterized by forth quantum number ms(spin)
What n
Principal quantum number which determines the total energy of atomic orbital. 1-infinity.
It defines distance from the nucleus
It also defines the orbital dimension( higher n=larger size of the orbital)
Orbitals with same n=same shell
What is l
Secondary quantum number. It defines shape of atomic orbital.
0- (n-1)
s p d f….
What is ml
Tells orientation of the orbital
-l to +l
What is ms
Spin magnetic quantum number
-1/2 or +1/2
What is characteristic of s orbital
Spherical shape
Characteristic of p orbital
2 lobes seperated by nodal plane
Characteristic of d orbital
4/5 orbitals have clover-leaf shape, they have 2 nodal planes
dz2 has 2 lobes on z axus and a ring around the center
What does energy of the orbitals depend on
For H-on princioal quantum number
For many electron atoms its both principal and secondary quantum number
What is aufbau principle
Building up the electronic structure of an atom by filling the lowest energy orbitals first(closest to nucleus)
Pauli exclusion principle
No 2 e- in the same atom can have all 4 quantum numbers the same. Only 2 electrons can occupy the same orbital and they have to have different spin
Hund’s rule
The ground state is the arrangment with the maximum number of parallel electrons
What is a group and what is a period
In a group elements have same configuration in the outermost shell(valence electrons). While in the period elements have same principal quantum number n
What are noble gases
They have the outermost shell(except He) (p-subshell) filled
Unreactive
Inert gases
What is octet
s²p⁶ configuration which is very stable
What is atomic radius
Half of the distance between the nuclei of neighbouring atoms in the pure element
How does atomic radius varies?
Bigger the group–>smaller
Bigfer the period–>bigger
In ions:
Anions–>larger
Cation–>smaller
Ionization energies
That is energy change when an e- is removed from an atom of the element in the gas phase
Higher the ionization–>more difficult to remove the e-
Every next ionozation energy is greater than the previous one
How does ionization energy vary
It becomes lower in the group and higher in a period
Electronic gain energy
Energy change that occurs when an electeon is attached to an atom in the gas phase. It can be enotermic or exothermic process for forst electron gain energy. For the second and higher its always endotermic process
Electron affinity and how does it vary
Ea-energy released of attachment of an e- to an atom. Exothermic->+ values; endothermic–> -values
In a group- smaller
In a period- larger
Electronegativity
Tendency of the atom to attracts e- to itself.
First ionization energy(EI1) and the electron affinity(Eea) are measure of the tendency of an atom to attract e-
X(electronegativity)=(E.I-A.E)/2
