Answer:
Explanation:
Selenium is a chemical element with the symbol Se and atomic number 34.
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Selenium
Melting point 494 K (221 °C, 430 °F)
Boiling point 958 K (685 °C, 1265 °F)
Density (near r.t. ) gray: 4.81 g/cm3 alpha: 4.39 g/cm3 vitreous: 4.28 g/cm3
when liquid (at m.p. ) 3.99 g/cm3
Answer:
More energy will be released from the old substance than the new substance will need to form it's chemical bonds.
Explanation:
Given
Chemical A and Chemical B react in an exothermic reaction.
This means energy is released when they react to give products. The product formation also requires energy, which is got from the energy released when A and B reacts. The energy that is left after the formation of products is released as heat. So in order for a reaction to be exothermic, the energy released by the reactants should be more than the energy required for the new chemical bonds to be formed to give the products.
Lines in one spectral series can overlap lines in another is rydberg
In several chemical elements, the Rydberg formula is used to compute the wavelengths of spectral lines.
<h3>
What causes lines in a line spectrum?</h3>
A spectral line is similar to a fingerprint in that it can be used to identify the atoms, elements, or molecules in a star, galaxy, or cloud of interstellar gas. When we use a prism to split incoming light from a heavenly source, we often observe a rainbow of colours crossed by definite lines. It's worth noting that spectral lines can appear in other parts of the electromagnetic spectrum, however we can't use a prism to assist us identify them.
Emission lines are distinct coloured lines that appear on a black backdrop and correspond to certain wavelengths of light emitted by an item.
Absorption lines are visible as black bars.
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the three categories of atomic solids are as follows;
E. nonbonding atomic solids.
A. network covalent.
What are atomic solids?
Atoms of an element must be bonded to other atoms of the same atom type in order for a substance to be considered an atomic solid.
Diamond, silicon crystals, and pure metals are a few examples of atomic solids. Network solids are atomic solids in which the atoms are covalently connected to one another.
SiO2, often known as quartz, is another example of a network solid and is an extremely hard substance, scoring 7.5 out of 10.
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