The rate at which work is done is called ___

Why has the atomic model changed over time

inysia [295]

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

7 0

2 years ago

What is the density of a substance that has a mass of 453g and a volume of 224mL?

Mrrafil [7]

Density is mass per unit volume. In this case, the unit is g/ml
Mass=453g ρ=453g/224ml
Volume=224ml ρ=2.022g/ml(rounded to nearest hundredth)
Density=?
ρ=mass/volume
Therefore the density of the substance is 2.022g/ml

6 0

3 years ago

Two particles of a gas collide. Why is this considered an elastic collision? (1 point)

dezoksy [38]

I don’t know really really I don’t know

7 0

2 years ago

Read 2 more answers

You have landed on an unknown planet, newtonia, and want to know what objects will weigh there. you find that when a certain too

AleksandrR [38]

Refer to the diagram shown.

Because the surface is frictionless, the resistive for, R, is zero.

Let m = the mass of the object.
Let a = acceleration due to the applied force.
Therefore
12.7 N = (m kg)*(a m/s²)
a = 12.7/m m/s²

The object travels 16.1 m in 2.5 s, starting from rest. Therefore
16.1 N = (1/2)*(12.7/m m/s²)*(2.5 s)² = 39.6875/m N
m = 16.1/39.6875 = 0.4057 kg

For freefall, let g = acceleration due to gravity.
The time to fall from 10.3 m is 2.88 s, therefore
10.3 m = (1/2)*(g m/s²)*(2.88 s)² = 4.1472g m
g = 10.3/4.1472 = 2.484 m/s²

Answer:
The gravitational acceleration on the planet is 2.5 m/s² (nearest tenth)