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LuckyWell [14K]
3 years ago
9

What is the atomic number of an element that has seven protons and eight neutrons and seven electrons?

Chemistry
2 answers:
Dmitrij [34]3 years ago
7 0

Answer:

Nitrogen has an atomic number of 7 (Z=7) because it has 7 protons in its nucleus. Some nitrogen atoms have an atomic mass number of 15 (A=15). A is the number of neutrons plus protons in the nucleus. However, we already know that there are 7 protons

Darya [45]3 years ago
6 0

Answer:

Atomic number = Number of protons = Number of electrons

Atomic number = 7

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How many moles of neon gas are there 25.0 L of gas or 5.0°C with a pressure of 89.9 KPa?
vladimir2022 [97]
  • Volume=25L
  • Temperature=5°C
  • Pressure=89.9kPa

Now

\\ \rm\rightarrowtail PV=nRT

\\ \rm\rightarrowtail n=\dfrac{PV}{RT}

\\ \rm\rightarrowtail n=\dfrac{89.9(25)}{5R}

\\ \rm\rightarrowtail n=89.9(5)/R

\\ \rm\rightarrowtail n=449.5/R mol

8 0
2 years ago
Why is the chemistry of actinoids complicated?
gladu [14]

Answer:

Explanation:

Actinoids are the series have 15 element in the periodic table.

Chemistry of actinoids are complicated because of the following reasons.

  • Their outer most orbitals are 6d and 7s but most of the electrons resides in 5f orbitals. These orbitals are most exposed to environment and incoming electron picked up by 5f orbital instead of 6d or 7s orbitals.
  • They are radioactive elements that couldn't be handle in normal condition to study their properties.
  • Their f-orbital can accommodate 14 electrons and they have many variable oxidation state.
  • 5d electron donot contribute in the formation of chemical bonds.
  • They have a very strong tendency to make complexes
  • Most of the actinoides are artificial and are in very minute in amount. they are in very less quantity that is amounts found in nano-grams so are more expensive too and
  • As they are radioactive so their half life is very short and in very less time the decay occur so couldn't be study as upon decay their actual properties changed.

Due to all the above reasons it make difficult for a chemist to study about the chemical properties of actinoids.

8 0
3 years ago
1. Imagine you have a sealed 20.0 L balloon filled with helium gas at 750 mmHg in the
SVETLANKA909090 [29]

Answer:

17.6510 L

Explanation:

First we should get the number of moles of helium here by Boyle's law

PV=nRT

P=750/760= 0.9868 atm

T=25+273=298 kelvin

R= 0.08206

V= 20L

so

n=PV/RT

n=0.9868×20/0.08206×298

n=0.80707 mol

Then use the same law

V=0.80707×0.08206×263/0.9869=

17.6510L

SO THE VOLUME WILL BE 17.6510 L

6 0
2 years ago
The temperature of a sample of iron with a mass of 10.0 g changed from 50.4°C to 25.0°C with the release of 47 calories of heat.
sleet_krkn [62]
This would be concidered a chemical reaction. 
6 0
3 years ago
I need answers plz<br>btw D says ice crystals ​
tangare [24]

Answer:

B. Hydrogen and oxygen molecules

General Formulas and Concepts:

<u>Chemistry - Reactions</u>

  • Reactants are always on the left side of the arrow
  • Products are always on the right side of the arrow

Explanation:

<u>Step 1: Define</u>

Reaction RxN:   2H₂ + O₂ → 2H₂O

<u>Step 2: Identify</u>

Reactants:   H₂ and O₂

Products: H₂O

7 0
2 years ago
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