There are several ways that atoms can combine. In one way, atoms are put together to form things called molecules. To understand molecules, you have to understand what an atom is made up of. Inside the atom, there’s things called neutrons, protons, and electrons. The neutrons and protons are all stuck together in the middle of the atom, making up what’s called the nucleus. The electrons are much lighter than the protons or neutrons, and they move all around the nucleus. For a picture of this, look at the answer to the question, Picture of an Atom.
Some atoms, though, want to have more or less electrons around them than they do. So they form things called bonds that let them share electrons with each other. (There are lots of different kinds of bonds, but this is the basic idea.) When they’re sharing electrons, they’re totally stuck together and become what’s called a molecule.
(added by Mike W.: Those types of bonds are called ionic bonds, where one atom grabs an electron from another and the resulting charged ions stick together by electrical attraction. Bonds can also form even between atoms which are just like each other, so that neither ends up with more or less electrons than it started with. Common examples are the oxygen and nitrogen molecules in the air. Here the reason that the atoms stick together is that the electron clouds, described a bit in that link above, can lower their energy by spreading out over two atoms instead of one, for reasons that one can’t begin to describe without quantum mechanics. these covalent bonds are very common and often the strongest bonds around.)
Some atoms, though, don’t want to have any more or less electrons than they have. So they don’t form bonds with any other atoms. (An example of this is Helium.) So they don’t bond at all. (Mike W.: What this really means is that every electron is stuck well, in a low energy state. The next state available would have much higher energy. Only very weak bonds can form with other atoms. The reasons why there are particular states around with different energies are also entirely due to quantum mechanics.))
(Mike W.) The second common way atoms combine is as crystals. they stick together for p[retty much the same reasons as atoms in molecules, but instead of making a little unit of fixed size, they just keep styacking up. The copper in a wire, for example, contains many copper atoms stacked up together. A salt crystal contains sodium and chlorine stacked up in an alternating pattern.
Another way that atoms can combine is by something called ’fusion.’ This is when the nucleus of one atom and the nucleus of another atom actually come together, making one bigger atom with all of the electrons going around it. This is much less common and very hard for scientists to do. When it happens, it creates a lot of energy, so it would be convenient if people knew how to control it. Unfortunately, as far as we know, in order to make two atoms combine by fusion, you have to use a whole lot of energy (make it very hot), so it’s really not a practical way of making energy yet. One place that fusion does happen frequently is in the very center of the sun, where it gets /extremely/ hot.
It's complicated. There are several factors for atom combination.
Each group of atoms on the periodic table has a certain number of valence electrons, which gives it a positive or negative charge. Atoms of the opposite charge are attracted to them. For example table salt, NaCl -- Na has a charge of +1 (it has 1 valence electron) and Cl has a charge of -1 (it has 7 valence electrons). Every atom except Helium and Hydrogen wants to have a total of 8 electrons (the octet rule), so they combine with that in mind.
For example water -- H2O. Hydrogen has 1 electron, +1 charge, wants 2 total. Oxygen starts with 6 electrons, (-2) charge, wants 8 total. Oxygen's 6 combine with Hydrogen's 2 to make 8, so 1 oxygen can bond with 2 hydrogens to have a zero net charge and still follow the octet rule.
There are also many types of bonds -- ionic (opposite charges attract), covalent (atoms share electrons instead of taking them from other electrons), and polar covalent (a covalent bond where the electronegativity of one atom is much higher than the other). Electronegativity trends larger from the bottom left of the periodic table, where it is smallest, to N, O, and F, where it is the largest. Flourine is the most electronegative element on the table and will bond indiscriminately with anything. It also has 7 electrons, -1 charge. HF would be an example of polar covalent, because F gets it's 8th electron and keeps it (from the H)
Check out this animation on polarity, it will explain a lot.
The type of electrons in an atom's outermost shell (the valence shell) governs its bonding habit. consequently, components with the comparable type of valence electrons are grouped jointly interior the columns of the periodic table of the climate. Alkali metals contain one electron on their outer shell; alkaline earth metals, 2 electrons; halogens, seven electrons; and diverse others. each atom is maximum good with an entire valence shell. this suggests that atoms with finished valence shells (the noble gases) are very unreactive. Conversely, atoms with few electrons of their valence shell are extra reactive. Alkali metals are consequently very reactive, with caesium, rubidium, and francium being the main reactive of all metals. additionally, atoms that choose in straightforward terms few electrons (such because of fact the halogens) to fill their valence shells are reactive. Fluorine is the main reactive of all components. Atoms could fill their valence shells by potential of chemical bonding. that's achieved considered one of two techniques: an atom can the two proportion electrons with different atoms (a covalent bond), or it could get rid of electrons from (or donate electrons to) different atoms (an ionic bond). The formation of a bond motives a solid charm between 2 atoms, growing to be molecules or ionic compounds. Many different sorts of bonds exist, jointly with: polar covalent bonds; coordinate covalent bonds; steel bonds; hydrogen bonds; and van der Waals bonds.
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There are several ways that atoms can combine. In one way, atoms are put together to form things called molecules. To understand molecules, you have to understand what an atom is made up of. Inside the atom, there’s things called neutrons, protons, and electrons. The neutrons and protons are all stuck together in the middle of the atom, making up what’s called the nucleus. The electrons are much lighter than the protons or neutrons, and they move all around the nucleus. For a picture of this, look at the answer to the question, Picture of an Atom.
Some atoms, though, want to have more or less electrons around them than they do. So they form things called bonds that let them share electrons with each other. (There are lots of different kinds of bonds, but this is the basic idea.) When they’re sharing electrons, they’re totally stuck together and become what’s called a molecule.
(added by Mike W.: Those types of bonds are called ionic bonds, where one atom grabs an electron from another and the resulting charged ions stick together by electrical attraction. Bonds can also form even between atoms which are just like each other, so that neither ends up with more or less electrons than it started with. Common examples are the oxygen and nitrogen molecules in the air. Here the reason that the atoms stick together is that the electron clouds, described a bit in that link above, can lower their energy by spreading out over two atoms instead of one, for reasons that one can’t begin to describe without quantum mechanics. these covalent bonds are very common and often the strongest bonds around.)
Some atoms, though, don’t want to have any more or less electrons than they have. So they don’t form bonds with any other atoms. (An example of this is Helium.) So they don’t bond at all. (Mike W.: What this really means is that every electron is stuck well, in a low energy state. The next state available would have much higher energy. Only very weak bonds can form with other atoms. The reasons why there are particular states around with different energies are also entirely due to quantum mechanics.))
(Mike W.) The second common way atoms combine is as crystals. they stick together for p[retty much the same reasons as atoms in molecules, but instead of making a little unit of fixed size, they just keep styacking up. The copper in a wire, for example, contains many copper atoms stacked up together. A salt crystal contains sodium and chlorine stacked up in an alternating pattern.
Another way that atoms can combine is by something called ’fusion.’ This is when the nucleus of one atom and the nucleus of another atom actually come together, making one bigger atom with all of the electrons going around it. This is much less common and very hard for scientists to do. When it happens, it creates a lot of energy, so it would be convenient if people knew how to control it. Unfortunately, as far as we know, in order to make two atoms combine by fusion, you have to use a whole lot of energy (make it very hot), so it’s really not a practical way of making energy yet. One place that fusion does happen frequently is in the very center of the sun, where it gets /extremely/ hot.
It's complicated. There are several factors for atom combination.
Each group of atoms on the periodic table has a certain number of valence electrons, which gives it a positive or negative charge. Atoms of the opposite charge are attracted to them. For example table salt, NaCl -- Na has a charge of +1 (it has 1 valence electron) and Cl has a charge of -1 (it has 7 valence electrons). Every atom except Helium and Hydrogen wants to have a total of 8 electrons (the octet rule), so they combine with that in mind.
For example water -- H2O. Hydrogen has 1 electron, +1 charge, wants 2 total. Oxygen starts with 6 electrons, (-2) charge, wants 8 total. Oxygen's 6 combine with Hydrogen's 2 to make 8, so 1 oxygen can bond with 2 hydrogens to have a zero net charge and still follow the octet rule.
There are also many types of bonds -- ionic (opposite charges attract), covalent (atoms share electrons instead of taking them from other electrons), and polar covalent (a covalent bond where the electronegativity of one atom is much higher than the other). Electronegativity trends larger from the bottom left of the periodic table, where it is smallest, to N, O, and F, where it is the largest. Flourine is the most electronegative element on the table and will bond indiscriminately with anything. It also has 7 electrons, -1 charge. HF would be an example of polar covalent, because F gets it's 8th electron and keeps it (from the H)
Check out this animation on polarity, it will explain a lot.
http://www.mhhe.com/physsci/chemistry/animations/c...
This is on bonding
http://www.mhhe.com/physsci/chemistry/animations/c...
http://www.youtube.com/watch?v=QqjcCvzWwww
Good luck!
The type of electrons in an atom's outermost shell (the valence shell) governs its bonding habit. consequently, components with the comparable type of valence electrons are grouped jointly interior the columns of the periodic table of the climate. Alkali metals contain one electron on their outer shell; alkaline earth metals, 2 electrons; halogens, seven electrons; and diverse others. each atom is maximum good with an entire valence shell. this suggests that atoms with finished valence shells (the noble gases) are very unreactive. Conversely, atoms with few electrons of their valence shell are extra reactive. Alkali metals are consequently very reactive, with caesium, rubidium, and francium being the main reactive of all metals. additionally, atoms that choose in straightforward terms few electrons (such because of fact the halogens) to fill their valence shells are reactive. Fluorine is the main reactive of all components. Atoms could fill their valence shells by potential of chemical bonding. that's achieved considered one of two techniques: an atom can the two proportion electrons with different atoms (a covalent bond), or it could get rid of electrons from (or donate electrons to) different atoms (an ionic bond). The formation of a bond motives a solid charm between 2 atoms, growing to be molecules or ionic compounds. Many different sorts of bonds exist, jointly with: polar covalent bonds; coordinate covalent bonds; steel bonds; hydrogen bonds; and van der Waals bonds.