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Answer: Mendeleev’s Periodic Table was built by listing the known elements in order of increasing atomic mass and grouping the elements by their properties (such as reactivity and formula of oxides). In one or two cases, he discovered that he had to put a lower atomic mass element after a higher atomic mass element because the table which went strictly by increasing atomic mass produced groups with inconsistent properties. He also left blanks in the table.</h3>
In modern times, we know that the elements in a given group (also known as a family or column) have the same number of valence electrons, with ground state configurations having a consistent pattern, for instance:
F 1s2 2s2 2p5, Cl 1s2 2s2 2p6 3s2 3p5, Br 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p5, etc.
Of course, the ground state configurations play a major role in determining how an element reacts and what compounds it forms. Thus, the elements in a given group have similar properties.
The structure of the table also predicts how the properties vary. For instance, atomic radius increases down a group as does metallic character.
<h3>Hope this helps have a awesome day/night✨</h3>
Explanation:
Answer:
Explanation:
This question asks us to find the new volume if the pressure changes. Therefore, we use Boyle's Law, which states that pressure and the volume of the gas are inversely proportional. The formula is:
We know that the original sample of gas occupies 4.5 liters at a pressure of 1.63 atmospheres. We know that the pressure was changed to 2.4 atmospheres, but we don't know the volume. Substitute all known values into the formula.
Since we are solving for the new volume (V₂), we need to isolate the variable. It is being multiplied by 2.4 atmospheres and the inverse of multiplication is division. Divide both sides by 2.4 atm.
The units of atmospheres (atm) cancel.
The smallest number of significant figures in the original measurements is 2, so our answer must have the same. For the number we found, that is the tenths place.
The 5 in the hundredth place tells us to round the 0 up to a 1.
The volume of the neon gas when the pressure is changed to 2.4 atmospheres is <u>3.1 Liters.</u>
It is a single replacement reaction. Li and Mg switch places.
Answer:
Explanation:
The following are the order of point from oldest to most recent
1. Atoms are tiny indivisible particles that make up all mater.
it is Postulate of Dalton's atomic theory. this theory was put forward in 1803
2. Negatively charged electrons are embedded in a mass of positive charge.
In 1897 J.J Thomson discovered that atom consist of tiny negatively charged particles called electrons that are uniformly spread in +vely charged matrix this model called as plum pudding model.
3. Atoms consist of mostly empty space with a dense nucleus of positive charge.
While doing experiment on gold foil Rutherford presented a model in 1909 and stated that atom consist mostly empty space with dense nucleus.
4. Electrons occupy specific energy levels surrounding a positively charged nucleus.
Niels Bohr in 1913 put forward a model to explain atomic orbitals/energy level. This is a postulate of Bohr model.
5. Electrons move about a positively charged nucleus in clouds that are defined by probabilities.
In 1926 Erwin Schrödinger explain the wave function of electrons and its probability.
