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reflection questions
1. summarize the physical and chemical properties of uranium.
2. in the lesson, many models were used to depict the atom. how does models you understand atomic structure?
3. how do protons, neutrons, and electrons differ in terms of their electrical charges and locations within the atom?
4. describe the four fundamental forces. which of these forces are involved in chemical bonding?

Explanation:

Q 1:

Summarize the physical and chemical properties of Uranium.

Physical properties:

Uranium is member of Actinide series.

Its atomic number is 92.

Its atomic mass is 238.0289 amu.

Its density is 18.95 g/cm³.

Its melting point is 1132 °C.

Its boiling point is 3818 °C.

Its vanderwaal radius is 0.121 nm.

It has eleven isotopes.

It is malleable and ductile.

Chemical properties:

It is used as primary material for the production of transuranium elements.

With oxygen it form oxides such as UO , U₂O₅, UO₃, UO₂, UO₄.2H₂ but most common form as U₃O₈ and UO₂.

It also form carbonates with oxidation state of VI.

It form halides with halogens. For example UO₂ react with HF and form UF₄.

UO₂ +  4HF  →  UF₄ + 2H₂O

It is used in bomb.

The first bomb made up of uranium was contained U-235. It start chain reaction and many uranium atom undergoes fission and produce large amount of energy.

The fertilizer such as phosphate contain large amount of uranium.

It is used in the production of steels and also in lamp.

Uranium-233 also used as nuclear fuel.

Q 2:

In the lesson, many models were used to depict the atom. How does models help you understand atomic structure?

Rutherford atomic model:

Atom consist of positive charges and most of the mass of an atom is concentrated in small region called nucleus but at that time Rutherford not aware of composition of this small region i.e, neutron and proton.

He stated that there are negatively charged particles revolve around the nucleus with a high speed.

Atom is neutral because it consist of negative charged electrons and positive nucleus equal in magnitude and there are strong electrostatic static forced between them.

The size of atom is greater than its nucleus.

Rutherford atomic model did not explain the stability of atom and also the arrangement of electrons in orbits.

Than in 1913 Bohr proposed that electrons are revolved in stable around the nucleus. He suggested that electron's angular momentum is quantized  and due to this quantization orbits have fixed energies and electron remain in its orbit can not jump into other orbit until it gain or lost the energy.

Q 3.

How do protons, neutrons, and electrons differ in terms of their electrical charges and locations within the atom?

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e-

Mass= 9.10938356×10-31 Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P+  

Symbol of neutron= n0  

Mass of proton=1.672623×10-27 Kg

Mass of neutron=1.674929×10-27 Kg

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.

Q 4:

Describe the four fundamental forces. Which of these forces are involved in chemical bonding?

Electromagnetic force

Explanation:

There are four fundamental forces:

Gravity

Weak nuclear force

Strong nuclear force

Electromagnetic force

Gravitational force is too weak that's why can not take part in chemical reaction while strong and weak nuclear forces are just involve in nuclear reaction not chemical reaction.

The only fundamental force which is electromagnetic force is take part in chemical reaction. This force is of different types depending upon the type of bonding. For example:

In covalent bond this type of force is occur between the atoms of almost equal electronegativity.

In ionic bond this force is occur is between positive and negative ions.

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