Answer:
The statement is considered to be true
Explanation:
The statement is true because when elements chemically combine, there are interactions between their valence electrons, causing the two elements to be bonded together to form what is known as a compound.
Compounds can only be formed from interactions between two or more elements. examples include:
Hydrogen + Oxygen = H2O (water)
Sodium + Chlorine = NaCl
Note that if atoms of the same element combine, what is formed is a molecule, not a compound. Some atoms usually do this to attain stability. examples include = O2 H2 and N2. They are oxygen molecule, hydrogen molecule, and nitrogen molecule respectively.
Compounds are only formed when different elements combine to attain electronic stability.
Answer:you should search on google
Explanation:
because its useful
When q is the heat energy in joules (J)
so, according to this formula, we can get q (in joule unit):
q = M*C*ΔT
when M is the mass of the water sample = 1.85 g
C is the specific heat capacity of water = 4.18 J/g.°C
and Δ T is the difference in temperature (Tf-Ti) = 33 - 22 = 11°C
So, by substitution, we will get the value of q ( in Joule):
∴ q = 1.85 g * 4.18 J/g.°C * 11 °C
= 85 J
Answer:
You will be able to watch the slow dissolution of the nail (probably a steel nail and not iron) and the change in colour of the solution.
Explanation:
I believe not 100% sure.
Answer:
- <em><u>Mendeleev produced the first orderly arrangement of known elements.</u></em>
- <em><u>Mendeleev used patterns to predict undiscovered elements.</u></em>
Explanation:
- <u>Mendeleev produced the first orderly arrangement of known elements and used patterns to predict the undiscovered elements.</u>
Those two statments are true.
For the time being there were some 62 known elements. Before Medeleev some schemes to order part of the elements were proposed, but Medeleev showed the relationship between the atomic mass and the properties of the elements (supports second choice). This arrangement is known as the periodic table.
More importantly, Mendeleev predicted correctly the existance and properties of unknown elements, which is his major contribution: he left blanket spaces which where gradually filled when new elements where discovered (this supports the fourth choice).
The first modern chemistry book was written by Antoine Lavoisier (this discards first option).
Mendeleev ordered the elements by increasing mass number (this discards third choice), which was corrected later by the scientist Henry Moseley, who ordered the elements by increasing atomic number (number of protons).
Isotopes were not known by Mendeleev times, so this discards the last option.
