In the Bohr's Model of the atom, the protons are located in the nucleus. The electrons move around the nucleus. I hope this helps in some way. (:
Ionic crystals are hard because of tight packing lattices, say, the positive and negative ions are strongly attached among themselves.
Sulfur, selenium, and tellurium
Answer:
From my side I think it is Photoreceptors cells :
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.
There are currently three known types of photoreceptor cells in mammalian eyes: rods, cones, and photosensitive retinal ganglion cells. The two classic photoreceptor cells are rods and cones, each contributing information used by the visual system to form a representation of the visual world, sight. The rods are narrower than the cones and distributed differently across the retina, but the chemical process in each that supports phototransduction is similar. A third class of mammalian photoreceptor cell was discovered during the 1990s: the photosensitive ganglion cells. These cells do not contribute to sight directly, but are thought to support circadian rhythms and pupillary reflex.
Explanation:
Force is measured in Newtons, which are units that equal 1 kg * m/sec 2. Force is measured in Newtons, N. Mass is measured in kilograms, kg. The unit that is used to measure force in the SI system of units is the Newton.
