In the early 20th century, the world came to know what they'd find at the core of every substance. Everything on this planet is made up of tiny atoms – and every atom has three fundamental particles known as neutrons, protons, and electrons.
With time, different scientists have made mind-blowing discoveries in various fields of science. And through these life-altering discoveries, we've learned the undeniable fact that everything is made of atoms.
The study of the atomic structure is compulsory for you if you become a student of physics.
The physics SAT prepares you well for your future in physics. If you're starting your SAT prep and want to score good grades in the Physics subject test, you must study atomic structure, energy, and other difficult topics.
If you want to crack the SAT physics exam, study the atomic structure topic carefully as it's the subject's bedrock. Other physics topics like forces have unique concepts you can use for the test.
Superprof has penned down an easy understanding and a complete syllabus of the physics subject for SAT prep.
We have covered several unique topics that may interest students in opting for physics, such as magnetism and electromagnetism.
Let's dive in a bit deeper to know more about the atomic structure!
Models Of Atom
If you want to study the atomic structure for exam prep, it's essential to understand the base first – the atom's models. Once you've wrapped your head around the basics, you can indulge in a practical approach to learning physics. That way, you will be able to tackle any physics problem the examiner gives you. Plus, you will learn how atoms are the basic building blocks of all matter. Give a quick read to the particle model of matters here.
Greeks were the first to study atoms. They discovered that all matter was made of millions of uncuttable pieces known as atomos. However, Sir Joseph Thomson, the late English Physicist, who discovered electrons centuries later after the Greek's idea of atoms, indicated that atoms are solid and, therefore, can't be crushed.
Students will also learn in this part about Rutherford's famous gold-foil experiment. He concluded that the atom is mainly void space; plus, it is full of positive charge particles.
Besides Thomson and Rutherford, this part will also cover other key developments in the atomic structure, such as Bohr and Chadwick's works on energy levels and neutrons, respectively.
Structure Of Atoms
Atoms are the smallest part of any ordinary matter and are about 10-10 meters in size. It includes a nucleus that contains neutrons and protons with tiny electrons revolving near the nucleus.
Within the atom, the neutrons and protons are the heaviest, and their total number is called atomic mass (or mass number). And the total protons within the atom are referred to as the proton number (or atomic number).
Isotopes can be defined as variants of different chemical elements with different neutron numbers and same proton numbers. For instance, there are three carbon isotopes and two chlorine isotopes.
Superprof will provide abundant information about isotopes in SAT physics lessons on the topic of atomic structure.
Normally, atoms are neutral. Plus, they've got the same proton and electron numbers. However, there are a few exceptions.
When atoms gain or lose electrons after the collision, they form ions that are either negatively or positively charged.
The negative charge appears when an atom gains an electron (can be more than one), and the positive charge appears when an atom loses an electron (also can be more than one).
When an atomic nucleus has incorrect neutron numbers, it rapidly collapses. This is known as radioactive decay.
Achieving Stable Nuclei
When the atom's nucleus has the same proton and neutron numbers, it becomes stable.
Every element found in the upper columns of a periodic table, with few protons, is stable if they've got the same amount of protons and neutrons.
Nonetheless, what's important to consider here is that when the proton numbers increase, the neutrons should also increase to ensure the atom's nuclei's stability.
Though nuclei with excessive or too little neutrons exist, they're bound to decay and emit radiation eventually.
Alpha decay is a form of radioactive decay. The atomic nucleus discharges the alpha particle and transforms into a distinct atomic nucleus, which has a reduced atomic and mass number by two and four.
In case the tiny nucleus contains excessive neutrons, the atom's proton also transforms into the neutron and discharges a fast-paced electron. This is called beta radiation or beta ray. In this decay, the mass number remains the same, but the proton number (also known as atomic number) increases by one.
When the beta or alpha particle is emitted, the nucleus loses a great amount of energy. To cool itself down, the nucleus emits a strong electromagnetic wave known as gamma-ray. Read more about the waves here. In this type of decay, both the mass number and an atomic number remain unchanged.
In the physics test of your SAT exam, many questions can be around radioactive rays, so it's better to thoroughly study these topics.
Though it's a given that all unstable atomic nuclei will decay, the time to decay varies. Even famous scientists can't predict a time of decay with precise calculations. There is only a logical deduction based on estimates and graphs.
Through half-life, it is possible to find out the nuclear decay. The Geiger-Muller tube can be used to measure and detect ionizing radiation.
Hazards And Uses Of Radiation
Let's admit it: we are exposed to some radiation in our daily lives. Though radiation is extremely useful when handled with great care and caution, but can be devastating if used recklessly.
Irradiation is a process in which the objects remain exposed to all forms of radiation. It has the potential to destroy living cells. Nonetheless, whether it's going to be a hazard or a boon depends on how the radiation will be used.
The following are a few useful ways of its usage:
- Use it to sterilize or disinfect fruits sold in the supermarkets to keep their preservation
- It can also be used for sterilizing various surgical instruments. Plus, the gamma-knives are used for killing cancerous tumors.
When the object has the presence of undesirable radioactive materials, it is called contamination. It is both beneficial and harmful. Some of the common contamination uses are:
- Detecting leaks: When the government (local or central) thinks there's a water pipe leakage in the supply line, they contaminate the pipe with gamma-emitting isotope. This way, it becomes easier to find leaks, which would otherwise be quite hard to spot.
- Medical contamination: Injected radioactive material like technetium-99 is a good source of a medical tracer. It induces soft tissues like kidneys or blood vessels to appear in various medical imaging tests. The isotope discharges the gamma-ray, which passes throughout the body quite easily.
It's a fact that we all live with low-level radiations, partly because some of the radioactive materials exist in the Earth naturally.
A few sources of this radiation are cosmic rays, radon gas, our drinks or foods, buildings, microwaves, etc. The SI unit to measure radioactivity is Becquerel (Bq).
Keeping all things aside, it's important to note here that radiations are extremely dangerous for humans if used without care' It causes severe damage to the body, including cataracts, sterility, skin rashes, damaged DNA, and cancer.
Nuclear Fusion And Fission
No doubt, the atomic nuclei carry a lot of energy that is still untapped. Realizing it would mean no more exclusive reliance on fossil fuels. It can be achieved through nuclear fusion and fission.
Nuclear fusion occurs when two (or more) small atomic nuclei come together to form new and different nuclei. Our Sun is the place where constant fusion reactions take place. One of the most common examples of nuclear fusion is when four hydrogen nuclei come together to form one helium nucleus.
One thing to note here is: almost in every fusion reaction, a slight amount of mass changes into energy.
Nuclear fission is the process where the large nuclei split into smaller atomic nuclei. The fragments that are formed after the fission reaction are called daughter nuclei. Plus, some other reactions also occur after the splitting, often termed as the 'chain reaction.'
All SAT subject tests are based on the MCQs, that require a thorough study of all SAT subjects, including Physics.
Within the physics SAT exam, the topic of the atomic structure and electricity is of paramount importance! However, you don't have to worry!
The Superprof physics tutor will explain various topics in this chapter, including radioactive decay, atoms, isotopes, radiation hazards and uses, etc.
Atomic structure in physics SAT is one of the key topics among a few others, such as space physics. Stay knowledgeable in this area, and you will achieve success in your SATs.