Models are often simplified. The small toy cars that you may have played with as a child are models. They give you a good idea of what a real car looks like, but they are much smaller and much simpler. A model cannot always be absolutely accurate and it is important that we realise this so that we don't build up a false idea about something.
In groups of 4-5, you are going to build a model of an atom. Before you start, think about these questions:
What information do I know about the structure of the atom? (e.g. what parts make it up? how big is it?)
What materials can I use to represent these parts of the atom as accurately as I can?
How will I put all these different parts together in my model?
As a group, share your ideas and then plan how you will build your model. Once you have built your model, discuss the following questions:
Does our model give a good idea of what the atom actually looks like?
In what ways is our model
inaccurate ? For example, we know that electrons
move around the atom's nucleus, but in your model, it might not have been possible for you to show this.
Are there any ways in which our model could be improved?
Now look at what other groups have done. Discuss the same questions for each of the models you see and record your answers.
The following simulation allows you to build an atom
run demo
This is another simulation that allows you to build an atom. This simulation also provides a summary of what you have learnt so far.
Run demo
Summary
Much of what we know today about the atom, has been the result of the work of a number of scientists who have added to each other's work to give us a good understanding of atomic structure.
Some of the important scientific contributors include
J.J.Thomson (discovery of the electron, which led to the Plum Pudding Model of the atom),
Ernest Rutherford (discovery that positive charge is concentrated in the centre of the atom) and
Niels Bohr (the arrangement of electrons around the nucleus in energy levels).
Because of the very small mass of atoms, their mass is measured in
atomic mass units (u).
.
An atom is made up of a central
nucleus (containing
protons and
neutrons ), surrounded by
electrons .
The
atomic number (Z) is the number of protons in an atom.
The
atomic mass number (A) is the number of protons and neutrons in the nucleus of an atom.
The
standard notation that is used to write an element, is
, where X is the element symbol, A is the atomic mass number and Z is the atomic number.
The
isotope of a particular element is made up of atoms which have the same number of protons as the atoms in the original element, but a different number of neutrons. This means that not all atoms of an element will have the same atomic mass.
The
relative atomic mass of an element is the average mass of one atom of all the naturally occurring isotopes of a particular chemical element, expressed in atomic mass units. The relative atomic mass is written under the elements' symbol on the Periodic Table.
The energy of electrons in an atom is
quantised . Electrons occur in specific energy levels around an atom's nucleus.
Within each energy level, an electron may move within a particular shape of
orbital . An orbital defines the space in which an electron is most likely to be found. There are different orbital shapes, including s, p, d and f orbitals.
Energy diagrams such as
Aufbau diagrams are used to show the electron configuration of atoms.
The electrons in the outermost energy level are called
valence electrons .
The electrons that are not valence electrons are called
core electrons .
Atoms whose outermost energy level is full, are less chemically reactive and therefore more stable, than those atoms whose outer energy level is not full.
End of chapter exercises
Write down only the word/term for each of the following descriptions.
The sum of the number of protons and neutrons in an atom
The defined space around an atom's nucleus, where an electron is most likely to be found
For each of the following, say whether the statement is True or False. If it is False, re-write the statement correctly.
and
each have 10 protons, 12 electrons and 12 neutrons.
The atomic mass of any atom of a particular element is always the same.
It is safer to use helium gas rather than hydrogen gas in balloons.
Group 1 elements readily form negative ions.
Multiple choice questions: In each of the following, choose the
one correct answer.
The three basic components of an atom are:
protons, neutrons, and ions
protons, neutrons, and electrons
protons, neutrinos, and ions
protium, deuterium, and tritium
The charge of an atom is...
positive
neutral
negative
If Rutherford had used neutrons instead of alpha particles in his scattering experiment, the neutrons would...
not deflect because they have no charge
have deflected more often
have been attracted to the nucleus easily
have given the same results
Consider the isotope
. Which of the following statements is
true ?
The element is an isotope of
The element contains 234 neutrons
The element has the same electron configuration as
The element has an atomic mass number of 92
The electron configuration of an atom of chlorine can be represented using the following notation:
Give the standard notation for the following elements:
beryllium
carbon-12
titanium-48
fluorine
Give the electron configurations and aufbau diagrams for the following elements:
aluminium
phosphorus
carbon
Use standard notation to represent the following elements:
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
When MP₁ becomes negative, TP start to decline.
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
ok
Shukri
how do you save a country economic situation when it's falling apart
Economic growth as an increase in the production and consumption of goods and services within an economy.but
Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has
The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50.
A,Calculate quantities of x and y which maximize utility.
B,Calculate value of Lagrange multiplier.
C,Calculate quantities of X and Y consumed with a given price.
D,alculate optimum level of output .
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product