usually, ionic bond occurs between metal and non metal
here Na is metal and Cl is non metal
so bond in NaCl is ionic bond
Electrons are shared differently in ionic and covalent bonds. Covalent bonds can be non-polar or polar and react to electrostatic charges.
Ionic bonds, like those in table salt (NaCl), are due to electrostatic attractive forces between their positive (Na+) and negative charged (Cl-) ions. In unit two, we compared atoms to puppies and electrons to bones in our analogy of how bonding works. In ionic bonding, each puppy starts out with an electron bone, but one puppy acts like a thief and steals the other puppy’s bone (see Fig. 3-1a). Now one puppy has two electron bones and one puppy has none. Because the electron bones in our analogy have a negative charge, the puppy thief becomes negatively charged due to the additional bone. The puppy that lost its electron bone becomes positively charged. Because the puppy who lost his bone has the opposite charge of the thief puppy, the puppies are held together by electrostatic forces, just like sodium and chloride ions!
In covalent bonds, like chlorine gas (Cl2), both atoms share and hold tightly onto each other’s electrons. In our analogy, each puppy again starts out with an electron bone. However, instead of one puppy stealing the other’s bone, both puppies hold onto both bones (see Fig. 3-1b).
Some covalently bonded molecules, like chlorine gas (Cl2), equally share their electrons (like two equally strong puppies each holding both bones). Other covalently bonded molecules, like hydrogen fluoride gas (HF), do not share electrons equally. The fluorine atom acts as a slightly stronger puppy that pulls a bit harder on the shared electrons (see Fig. 3-1c). Even though the electrons in hydrogen fluoride are shared, the fluorine side of a water molecule pulls harder on the negatively charged shared electrons and becomes negatively charged. The hydrogen atom has a slightly positively charge because it cannot hold as tightly to the negative electron bones. Covalent molecules with this type of uneven charge distribution are polar. Molecules with polar covalent bonds have a positive and negative side.
the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.
the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.
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sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.
if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.