An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so small that accurately predicting their behavior using classical physics—as if they were tennis balls, for example—is not possible due to quantum effects.
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. More than 99.94% of an atom's mass is in the nucleus. The protons have a positive electric charge, the electrons have a negative electric charge, and the neutrons have no electric charge. If the number of protons and electrons are equal, then the atom is electrically neutral. If an atom has more or fewer electrons than protons, then it has an overall negative or positive charge, respectively – such atoms are called ions.
The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force. The protons and neutrons in the nucleus are attracted to each other by the nuclear force. This force is usually stronger than the electromagnetic force that repels the positively charged protons from one another. Under certain circumstances, the repelling electromagnetic force becomes stronger than the nuclear force. In this case, the nucleus splits and leaves behind different elements. This is a form of nuclear decay.
The number of protons in the nucleus is the atomic number and it defines to which chemical element the atom belongs. For example, any atom that contains 29 protons is copper. The number of neutrons defines the isotope of the element. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals. The ability of atoms to associate and dissociate is responsible for most of the physical changes observed in nature. Chemistry is the discipline that studies these changes.
Homework Statement
You are given a 250mg tablet of Vitamin C, C6H8O6. How many atoms are in the Vitamin C sample?
The Attempt at a Solution
Formula Mass = 6(12.01)+8(1.01)+6(16.00) = 176.1 g/mol
250mg (1g/1000mg)(1mole/176.1g)(6.02e23molecules/1mole) = 8.546 molecules
How do I...
I need to identify two repulsive forces and two attractive forces that influence the formation of chemical bonds between two atoms.
this is what i understand so far:
1.chemical bonds between two atoms--> this is intermolecular forces
2.type of intermolecular forces--> Dipole dipole, van...
1. How are ions formed from atoms?
Attempt at Solution: From reading books and browsing on the internet I've collected a good amount of information, but I don't completely understand them.
"An ion is formed when an atom gains or loses an electron in bonding with another atom, causing the...
I'm trying to work out the amount of charge needed for atoms to leave the surface of a solid.
Here's the scenario, if we have a solid, say a metal for example, and we take some charge out of a certain area of the metal so it is just leaving the surface of the metal, we have a space charge...
i am having a bit of trouble with this question, and its not explained very clearly in our textbook...
"what are the RMS speeds of helium an dargon in a gas at 1000 degrees C"
any help would be greatly appreciated. physics is definitely not one of my strengths...
=D
cheers.
KC
Homework Statement
A structural I beam is made of iron> A view of its cross-section and its dimensions is shown in the figure, where d = 2 cm, w= 31 cm, h= 28 cm and the length (not shown) of the beam is L= 1.53 m.
The density of iron is 7560 kg/m^3. The atomic weight of iron is 55.85 g/mol...
Please add this title: Calculating the mass and number of atoms of a structural I beam.
Homework Statement
A structural I beam is made of iron> A view of its cross-section and its dimensions is shown in the figure, where d = 2 cm, w= 31 cm, h= 28 cm and the length (not shown) of the beam...
Hi, I have a thermodynamics problem which I tried to solve but have no idea whether my attempt has been succesful. Here is the problem:
Initially the translational root mean squared speed of an atom of a monatomic
ideal gas is 250 m/s. The pressure and volume of the gas are each doubled...
Is there a way to find the distance between atoms? For example, if you have a pure gold film... how can you find out how far the gold atoms are spaced?
Why does light not pass through voids within atoms??
Wow, i luuuuuvvvvv this site. for years I've had a fascination but rarely found many answers on many things. so a BIG thanks to some of you have been answering some of my questions so far.
Here's another...
When doing a fibre optic...
Are atoms 'perpetual machines'? To me it seems they are? Does friction affect electrons at all?
For example, A rock's atom's electrons have been orbiting the nucleus for the past, say 4 billion years without energy being supplied to the atom... Thanks for your input.
A monochromatic point source of light radiates 25 W at a wavelength of 5000 angstroms. A plate of metal is placed 100 cm from the source. Atoms in the metal have a radius of 1 angstrom. Assume that the atom can continually absorb light. The work function of the metal is 4 eV. How long is it...
Several questions they may not be all answerable but hey :D
How do proton and neutrons stay together? If one's got a positive charge and one's got a neutral charge there's nothing holding them together?
Once a proton is split from a neutron and/or it's nucleus would you be able to bind them...
Hello I was wondering if someone could tell me what is in the empty space of an atom. Or if it's actually empty why doesn't it fill up with something or collapse?
Thanks for taking the time to answer what I hope isn't too dumb a question:smile:
Nancy
the density of ice(solid) is less than that of water(liquid) and density of mercury(liquid) is more than that of many solids.
thinking about it, it seemed natural to me that the more closely are the atoms or molecules packed the greater will be their density. but on packing them closely, isn't...
Let's say, for ease of reference, an electron strikes a mercury atom with just enough energy such that this mercury atom is excited to another energy level. What would happen if a photon struck this atom with the same amount of energy? I remember encourtering a True/False problem like this in a...
We can easily write down configuration of electrons in an atom of given element. The question is how can I calculate the magnetic moment of given atom knowing configuration of electrons in that atom? Or maybe some other data is needed? Especially I am interested in calculation of magnetic moment...
For a chain of masses lying on a horizontal frictionless surface, with each mass connected to its neighbour mass by a spring of force constant s, the equation of motion for the nth mass is:
m(x_n)'' = -s[2(x_n) - x(n-1) - x(n=1)]
Where: x_n is the displacement of the nth mass from its...
Wave functions that produce two lobes of electron probability on opposing sides of the core indicate that our point-like electron must tunnel through the nuclear core when the point charge moves to the opposing lobe. I don't understand what is the driving force for this process? Does this...
I recently had some thoughts about the big "space" between electrons and the nuclei and how weird it would be if that space were truly "empty". This led me to try to understand exactly what was empty space and the more I thought about it, the more I began to think about dark matter. I know empty...
Homework Statement
An experiment is performed on a sample of atoms known to have a ground state of -5.0eV. The gas is illuminated with "white light" (400-700 nm). A spectrometer capable of analyzing radiation in this range is used to measure the radiation. The sample is observed to absorb...
Homework Statement
(a) What is the minimum energy (in electron volts) that is required to remove the electron from the ground state of an ionized atom (Z=2)? (b) What is the ionization energy for this ion?
Homework Equations
After doing what I got the answer for part (b)... but I don't...
hello,
I am curious about born repulsion of atoms, ie short range repulsion energy term proportional to 1/r^n. I find this in many solid state type books and they all call it the born repulsion and give no hints to its derivation or where it comes from. In _Atomic Physics_ 6th ed. by Max...
I get the photo-electric effect but I am just wandering, is that the only principal on which lasers function? I mean do lasers "cut" materials by ionizing the atoms?
A few questions about atoms splitting and some about "cold fusion"
Ok first I was thinking, when atoms fuse, they release energy, when an atom is split... it releases energy. Now, since energy is not created nor destroyed but only transferers, if you fuse an atom and then split it again, what...
I have seen some pictures of atoms taken by IBM, they seem like blurred round balls. Even other pictures with sophisticated instruments give a similar view. Are these pictures real ? Can they be trusted ? I ask this because electrons cannot be seen in any way aside from the fact that they are...
Hi all, I am having a hard time understanding the following scenario (I'm quoting from page 305 of the "Electricity & Magnetism" textbook which you can access via Google Books):
"Assume a simple model for an atom which consists of a point nucleus (+q) surrounded by a uniformly charged...
After ingestion of glucose, trace the path of the hydrogen atoms in glucose beginning within the digestive tract and ending with the oxidation of the glucose during aerobic respiration. Can anyone help me out with this problem?
Thanks to everyone in advance!
I draw the formula without octet on sulfur and it says to draw it with octet on all atoms...I don't know what to do with the 2 electrons on sulfur or how to do it...thanks
I'm a little confused about something very simple. From a chemistry perspective I am told about how many electrons fit into each type of orbital. For instance, 1s and 2s can only have two each, the 2p orbitals total 6. It is composed of the Px, Py, and Pz and only two can be in each set, while...
Homework Statement
(a) How many atoms of helium gas fill a balloon of diameter 29.4 cm at 23.5°C and 1.00 atm?
(b) What is the average kinetic energy of the helium atoms?
(c) What is the root-mean-square speed of the helium atoms?
Homework Equations
P=2/3[N/V][1/2mv^2]...
Hi,
I read this article on quantum entanglement of beryllium atoms:
http://www.physorg.com/news80396930.html
I have read other similar articles on the entanglement of photons and I understand that the spin of two photons can become entangled.
My question is, when...
Using the first order perturbation theory I will determine the probability of finding some atoms in a certain state. The electric field is directed along the z-axis. But i don't understand how this is done.
Should I convert the hydrogen atoms state equations into cartesian coordinates or...
"Artificial atoms" used to improve compact discs?
This should be very entertaining for all of you. If you visit http://machinadynamica.com/ you will find many interesting devices. Some of them are complete bunk (for example, the "Clever Little Clock", the "Brilliant Pebbles", and the...
Homework Statement
What is the RMS speed of Helium atoms when the temperature of the Helium gas is 247 K? (Possibly useful constants: the atomic mass of Helium is 4.00 AMU, the Atomic Mass Unit is: 1 AMU = 1.66×10-27 kg, Boltzmann's constant is: kB = 1.38×10-23 J/K.)
What would be the RMS...
I know of the four fundamental forces ie the strong and weak nuclear forces, gravity and electromagnetism, but what is the force that holds atoms together in a substance and why is this force not considered a fundamental force?
Is there any evidence or even a theory that all Atoms are the same size?
I was wondering what affect if the Big Bang or Bangs theory is correct, what difference if any would be found in the first atoms and the last atoms ever made?
Was it a production line of atoms and would that mould not...
I'm new here and don't know anything about Quantum Physics but I love the concepts and ideas that surround the theories.well I know it sounds silly but is it possible?
Its something I was thinking about when talking about Absolute Zero, they have used so many methods to slow the atom down so I...
I am a little bit confused.
If U235 decays 2 neutrons, and the two daughter atoms posses a larger amount of binding energy per nucleon, then why is there excess energy? Why doesn't this process require the input of additional energy? I know I am missing something fairly simple.
The following link shows how to calculate the size of an atom, where can I find a chart where this has been done for all the elements in the periodic table? I know you can get charts of atomic radius but those are based on the distance between the nucleus of two bonded atoms and therefore the...
Ok so I just started taking this Bio 12 class after not being in High School for over 5 years!
It is not what I thought it would be at all!
Im kind of getting stuck on one topic and no matter who I talk to I still don't understand it.
What is the dif between Atoms and Elements?
I...
Calculate the number of moles of O atoms in 13.27 g Mn(NO3)2.
Hi I did this question and it seemed pretty easy but there is this online assignment I am doing it for and it says I am not getting the right answer.
Please can someone try it and see if they get what i do, or tell me what I am...
Hi. This isn't so much a homework question, but more of a conceptual understanding question.
Lets say an atom has a ground energy level defined at 0J.
The energy levels are:
E1 = 0 J
E2 = 7.77*10^-19 J
E3 = 10.66*10^-19 J
E4 = 14.1*10^-19 J
E5 = 16.6*10^-19 J
Now, if an electron...
I have a question about the electrons in atoms. This question is from quantum mechanics, but it is really a situation of classical electrodynamics. When the electron goes around the nucleus, it is said that the electron will emit electromagnetic wave and then fall to the nucleus. But in fact all...