If the atoms are mostly empty, why things are hard to touch and to look at?
Chemist John Dalton proposed the theory that all matter is composed of particles and objects - atoms - and this theory is still accepted by the scientific community, after two hundred years. Each of these atoms consists of extremely small core and has less electrons which move at a relatively large distance from the center. If we imagine a table, which is a billion times more of its atoms will be the size of a watermelon. But even then, in the center of the core will still be too small, so that it can be seen, not to mention the electrons. Why, then, our fingers do not pass through the atoms? Why the light does not penetrate through the cracks?
To understand this, we need to consider the electrons. Unfortunately, in school we were taught simplistic notions - electrons do not actually revolve around the center of the atom, the planets around the sun. Although we were told so. Instead, the electrons can be written as a swarm of bees or a flock of birds, some movements that are too fast, that they could catch, but you still see the overall shape of the swarm.
In fact, the electrons dance - and there is no better word to describe this process. But this is not a random dance - rather, ballroom dance, in which the electrons move in a specific pattern by following the steps set out a mathematical equation named Erwin Schrödinger.
These schemes, models can vary - some slow and gentle, as the waltz, others fast and energetic, like to boogie. Each electron adheres to the same scheme, but sometimes it can switch to another, if no other electron has this scheme does not comply. No two electrons in an atom can not move the same way: it is usually called the principle of the ban, the Pauli exclusion principle.
Although electrons are never tired, the transition to a faster step requires energy. When an electron is transferred to a slow circuit, it loses energy. Therefore, when the energy in the form of light falls on an electron, it can absorb some energy and move to a faster, higher "dance". A beam of light does not pass through your desk, because the electrons in the atoms of all try to capture a little bit of energy from the light.
After some time, they lose the energy received, sometimes in the form of the same light. Changes in the nature of absorption and reflection of light gives us reflections and colors - so we can see a table as a solid object.
The resistance when touching the
Why is it so strongly and feel? You may have heard that this is due to the repulsive - that the two negatively charged object must repel each other. But this is not the case. Hard it is also because of the dancing electrons. If the touch table, electrons from the atoms in your fingers will close to electrons in the atoms of the section. And when the electrons in one atom closer to the core in another, the circuit changing their dance. Because electrons in the low energy state near one nucleus can not do the same next to each other - this place is already taken. Newcomer has to go into an idle position. And excess energy you need somewhere to put, not in the form of light at this time, and in the form of power of your finger touches.
Therefore, the process close summing atoms requires energy, because all their electrons must move to other unoccupied, high-energy state. Attempt to combine all the atoms of the table and fingers together will require enormous amounts of energy - more than can provide your muscles. Do you feel the resistance of the finger, and the table felt the hardness of your body when you touch.