The first model of the atom was developed by JJ Thomson in 1904, who thought that atoms were composed purely of negatively charged electrons. This model was known as the 'plum pudding' model.
This theory was then disproved by Ernest Rutherford and the gold foil experiment in 1911, where Rutherford shot alpha particles at gold foil, and noticed that some went through and some bounced back, implying the existence of a positive nucleus.
In 1913, Niels Bohr proposed a model of the atom where the electrons were contained within quantized shells that orbited the nucleus. This was because it was impossible for the cloud of negative electrons proposed by Rutherford to exist, as the negative electrons would be drawn to the positive nucleus, and the atom would collapse in on itself.
In 1926, the Austrian physicist Erwin Schrödinger created a quantum mechanical model of the atom by combining the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom.
However the model used today is closest to the Bohr model of the atom, using the quantized shells to contain the electrons.
For more info:
http://chemistry.about.com/od/chemistryglossary/a/debroglieeqdef.htm
bobo mag isip ayaw mag aral bobi
Explanation:
bobo ka boboboboboob
Answer:
a) 19.2 s
b) No
Explanation:
Given:
v₀ = 125 m/s
a = -6.5 m/s²
v = 0 m/s
a) Find: t
v = at + v₀
(0 m/s) = (-6.5 m/s²) t + (125 m/s)
t ≈ 19.2 s
b) Find: Δx
v² = v₀² + 2aΔx
(0 m/s)² = (125 m/s)² + 2 (-6.5 m/s²) Δx
Δx ≈ 1200 m
An aircraft carrier that's 850 meters long won't be long enough.
<h3>
Answer:</h3>
172.92 °C
<h3>
Explanation:</h3>
Concept being tested: Quantity of heat
We are given;
- Specific heat capacity of copper as 0.09 cal/g°C
- Quantity of heat is 8373 calories
- Mass of copper sample as 538.0 g
We are required to calculate the change in temperature.
- In this case we need to know that the amount of heat absorbed or gained by a substance is given by the product of mass, specific heat capacity and change in temperature.
Therefore, to calculate the change in temperature, ΔT we rearrange the formula;
ΔT = Q ÷ mc
Thus;
ΔT = 8373 cal ÷ (538 g × 0.09 cal/g°C)
= 172.92 °C
Therefore, the change in temperature will be 172.92 °C
<span> Let’s determine the initial momentum of each car.
#1 = 998 * 20 = 19,960
#2 = 1200 * 17 = 20,400
This is this is total momentum in the x direction before the collision. B is the correct answer. Since momentum is conserved in both directions, this will be total momentum is the x direction after the collision. To prove that this is true, let’s determine the magnitude and direction of the total momentum after the collision.
Since the y axis and the x axis are perpendicular to each other, use the following equation to determine the magnitude of their final momentum.
Final = √(x^2 + y^2) = √(20,400^2 + 19,960^2) = √814,561,600
This is approximately 28,541. To determine the x component, we need to determine the angle of the final momentum. Use the following equation.
Tan θ = y/x = 19,960/20,400 = 499/510
θ = tan^-1 (499/510)
The angle is approximately 43.85˚ counter clockwise from the negative x axis. To determine the x component, multiply the final momentum by the cosine of the angle.
x = √814,561,600 * cos (tan^-1 (499/510) = 20,400</span>