Compare and contrast how are atoms and molecules the same and how are they different

Molecules are groups of atoms that have chemically bonded together.

A chemical bond is where one atom sticks to another.
Atoms are themselves groups of particles. They have protons and neutrons in a heavy solid mass in the middle known as the nucleus, with electrons orbiting the outside. Protons are positive and neutrons have no charge - neutrons are practically lumps of rock on the subatomic scale - so the nucleus is overall positive, while the orbiting electrons are negative.
Atoms have the same number of protons and electrons. Electrons are organised into shells or energy levels, which only have certain capacities - when one is full, you have to start putting electrons on the next shell out. Atoms would like their outer or valence shell to be full, because that means they are stable - they don't react any more.
When atoms bonds, they share or give away electrons to other atoms to fill their outer shells. Covalent bonding is when they share, which binds two atoms together, because without the other, neither would have a satisfied outer shell. Covalently bonded atoms are look blood brothers.
Ionic bonds are more like blood donors. These occur only between metal and non-metal atoms. The metal gives away its extra electrons to the non-metal, which means the metal becomes more positive (as it loses a negative thing, and
− − = + ) and the non-metal becomes negative. Like North and South on magnets, the positive and negative ions stick together. An ion is an atom which has a different number of electrons to protons, and so has a positive or negative electrical charge.
Exclusively between metals you can have a third type of bonding - metallic. This is where the metals give up their extra electrons which float around freely - thus allowing metals to conduct heat and electricity, which is energy that passes through, carried by free electrons. Because electrons are negative and the metal nuclei are positive, they are attracted to each other, and metals stick together around this sea of electrons.
Through these types of bonding, atoms can stick together to form molecules.

  sequence  is a continuous and distinctive band of  stars  that appears on plots of stellar  color  versus  brightness. these color-magnitude plots are known as  hertzsprung–russell diagramsafter their co-developers,  ejnar hertzsprungand  henry norris russell. stars on this band are known as  main-sequence stars  or  dwarf stars. these are the most numerous true stars in the universe, and include the earth's  sun.after condensation and ignition of a star, it generates  thermal energy  in its dense core region through  nuclear fusion  of  hydrogen  into  helium. during this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and age. the cores of main-sequence stars are in  hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of  gravitational collapse  from the overlying layers. the strong dependence of the rate of energy generation on temperature and pressure to sustain this balance. energy generated at the core makes its way to the surface and is radiated away at the  photosphere. the energy is carried by either  radiation  or  convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.the main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. stars below about 1.5 times the  mass of the sun  (1.5  m☉) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the  proton–proton chain. above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of  carbon,  nitrogen  and  oxygen  as intermediaries in the  cno cycle  that produces helium from hydrogen atoms. main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. below this mass, stars have cores that are entirely radiative with convective zones near the surface. with decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases. main-sequence stars below 0.4  m☉undergo convection throughout their mass. when core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.in general, the more massive a star is, the shorter its lifespan on the main sequence. after the hydrogen fuel at the core has been consumed, the star  evolves  away from the main sequence on the hr diagram, into a  supergiant,  red giant, or directly to a  white dwarf.