18.The octet rule tells us that in every chemical
reactions, elements will either gain or lose electrons to attain the noble gas electron
configuration. This stable<span> electron configuration is known as the octet configuration
since it is composed of 8 valence. Oxygen’s electron configuration is 1s2 2s2
2p4. So when</span> oxygen reacts with
other elements to form compounds, it completes the octet configuration by
taking 2 electrons from the element
it reacts with
19. Actually pure metals are made up not of
metal atoms but rather of closely packed cations (positively charge particles).
These cations are then surrounded by a pack of mobile valence electrons which
drift from one part of the metal<span> to
another. This is called metallic bond.</span>
20. This is the
energy which is needed to break a single bond. When the dissociation energy is
large, this means that the compound is more stable. Since carbon to carbon
bonds have high dissociation energy, therefore they are not very reactive.
21. Network solids are type of solids
in which the atoms are covalently bonded to one another, so they are very
stable. It takes higher temperature to melt them because breaking these
covalent bonds required greater energy. Some examples are:
- Diamond
<span>-Silicon Carbide</span>
Below are some conversions.
336.715 m/s
1212.175 km/h
753.206 mph
1104.709 ft/s
654.08 knots
Try using this website:
www.sengpielaudio.com/calculator-speedsound.htm
Answer:
1.57×10²³ molecules
Explanation:
Given data:
Number of molecules of ethanol = ?
Volume of ethanol = 15.0 mL
Density of ethanol = 0.789 g/mL
Solution:
Mass of ethanol :
Density = mass/ volume
0.789 g/mL = mass/ 15.0 mL
Mass = 0.789 g/mL× 15.0 mL
Mass = 11.84 g
Number of moles of ethanol:
Number of moles = mass/molar mass
Number of moles = 11.84 g / 46.07 g/mol
Number of moles = 0.26 mol
1 mole contain 6.022×10²³ molecules
0.26 mol × 6.022×10²³ molecules / 1mol
1.57×10²³ molecules
