Chemistry is the science of matter — its composition, structure, properties, and the reactions by which it transforms. It spans from atomic structure and the periodic table to the complex molecular interactions in living cells. Read more
Which element has the atomic number 1?
EasyHydrogen has the atomic number 1, meaning every hydrogen atom has exactly one proton in its nucleus. It is the first element on the periodic table.
Most of the hydrogen on Earth is not found as a gas but is "trapped" in molecules like water H_2O and organic matter!
Which acid is present in an ant's sting?
MediumFormic acid CH_2O_2 is the acid present in an ant's sting. When an ant bites or stings, it injects this acid to cause irritation and defend itself. The name "formic" comes from the Latin word "formica," which means "ant."
Some birds actually rub ants on their feathers (a behavior called "anting") to use the formic acid as a natural pesticide against mites!
What is the chemical formula for Baking Soda?
MediumThe chemical formula for Baking Soda (Sodium Bicarbonate) is NaHCO_3. It is a salt composed of a sodium cation and a bicarbonate anion.
In addition to baking, it's used in toothpaste to help whiten teeth and in refrigerators to absorb bad odors!
What is the energy of motion called?
EasyKinetic energy is the energy an object possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. The formula is KE = frac12mv^2.
If you double the speed of a car, its kinetic energy actually quadruples, which is why high-speed crashes are so much more dangerous!
What is the atomic number of Carbon?
MediumThe atomic number of Carbon is 6, meaning it has six protons in its nucleus. Carbon is the fundamental building block of all known life on Earth because of its unique ability to form stable bonds with many elements, including itself.
Carbon can exist in very different forms, from the soft, black graphite in your pencil to the hard, clear diamond in jewelry!
What is the chemical symbol for Gold?
EasyThe chemical symbol for Gold is Au, which comes from the Latin word "aurum," meaning "shining dawn." Gold is a transition metal known for its distinct yellow color, malleability, and resistance to corrosion.
Gold is so malleable that a single ounce can be beaten into a translucent sheet covering nearly 100 square feet!
What is the value of 'g' (acceleration due to gravity) on Earth?
EasyThe standard value of 'g' (the acceleration due to gravity) on Earth's surface is approximately 9.81 m/s^2. This means that in the absence of air resistance, the velocity of a falling object increases by about 9.8 meters per second every second.
The value of 'g' is slightly higher at the poles and lower at the equator because the Earth is not a perfect sphere!
What is the chemical symbol for Iron?
EasyThe chemical symbol for Iron is Fe, which comes from its Latin name "ferrum." Iron is a transition metal that is vital for life (as a part of hemoglobin in blood) and for modern industry (as the main component of steel).
Iron is what makes Mars look red; the planet's surface is covered in iron oxide, which is essentially the same thing as common rust!
What is the purest form of Carbon?
MediumDiamond is often considered the purest natural form of carbon. While graphite and coal are also forms of carbon, they often contain more impurities. Diamond consists of a very regular and tight lattice of carbon atoms.
Under extreme pressure and temperature, it is possible to turn common graphite (pencil lead) into real diamonds in a laboratory!
What is the valency of Magnesium?
MediumThe valency of Magnesium is 2. This means that magnesium atoms typically lose two electrons to form a Mg^2+ ion in order to achieve a stable electron configuration. It is an alkaline earth metal with the atomic number 12.
Magnesium is highly flammable and burns with a brilliant, blinding white light; it was once used as the main component in camera flash powder!
Which gas is evolved during the action of acid on metals?
HardHydrogen gas H_2 is evolved when a dilute acid reacts with a reactive metal (like zinc, iron, or magnesium). The reaction produces a salt and releases hydrogen gas as bubbles.
You can test for the presence of this hydrogen gas by holding a lit match to the mouth of the test tube; if hydrogen is present, it will ignite with a characteristic "pop" sound!
Which acid is found in vinegar?
MediumAcetic acid CH_3COOH is the acid found in vinegar. Household vinegar is typically a solution of about 5% to 8% acetic acid in water. It is produced by the fermentation of ethanol by acetic acid bacteria.
The word "vinegar" comes from the Old French "vin aigre," which literally means "sour wine"!
What is the main component of Biogas?
MediumMethane CH_4 is the main component of biogas, typically making up 50% to 75% of its volume. Biogas is produced by the breakdown of organic matter (like agricultural waste or manure) by bacteria in the absence of oxygen.
Methane is a potent greenhouse gas, and a significant amount of it is produced by the digestive systems of cows and other livestock!
What is the 'Three Rs' of environment?
EasyThe 'Three Rs' of the environment stand for Reduce, Reuse, and Recycle. They are the three best ways to minimize the amount of waste we create and to conserve natural resources and energy. "Reduce" is the most important, as it prevents waste from being created in the first place.
Some environmentalists have added a fourth and fifth 'R'-"Refuse" (saying no to single-use items) and "Rot" (composting)!
What is the symbol for Mercury?
MediumThe symbol for Mercury is Hg, which comes from its Greek-Latin name "hydrargyrum," meaning "water-silver" or "liquid silver." Mercury is unique because it is the only metal that is liquid at standard room temperature and pressure.
Because it is so dense, a solid iron ball will actually float on the surface of liquid mercury!
Which rock is formed from the transformation of existing rock?
EasyMetamorphic rocks are formed from the transformation of existing rock types (igneous, sedimentary, or other metamorphic rocks) through high heat and pressure. This change happens while the rock remains in a solid state.
The "metamorphosis" that rocks undergo is similar to how a caterpillar turns into a butterfly-it changes into something completely different without ever melting!
Who is known for the equation E=mc²?
EasyAlbert Einstein is famous for the equation E=mc^2, which he published in 1905 as part of his Special Theory of Relativity. The equation states that energy E is equal to mass m multiplied by the speed of light c squared. This revealed that mass and energy are actually different forms of the same thing and that a tiny amount of mass can be converted into a massive amount of energy.
This equation is the fundamental principle behind how the Sun produces energy and how nuclear power plants generate electricity!
What is acceleration due to gravity (m/s²)?
HardThe standard acceleration due to gravity on the surface of the Earth is approximately 9.8 m/s^2 (or 32.2 ft/s^2. This means that if you drop an object in a vacuum, its velocity will increase by about 9.8 meters per second for every second that it falls. This value varies slightly depending on where you are on Earth, being stronger at the poles and weaker at the equator.
Because the Earth is not a perfect sphere and is slightly "bulgy" at the equator, you actually weigh a tiny bit less at the equator than you do at the North Pole! The difference is only about 0.5%, so a person weighing 200 lbs would lose about 1 lb just by traveling from the pole to the equator.
Which layer protects Earth from UV radiation?
EasyThe ozone layer, located in the stratosphere, protects the Earth from harmful ultraviolet (UV) radiation. Without this layer, life on land would be impossible as the intense UV rays would damage DNA and cause severe health issues for all living things.
In the 1980s, scientists discovered a massive "hole" in the ozone layer over Antarctica, which led to a global ban on the chemicals (CFCs) that were causing it!
What is the main contributor to the carbon footprint?
MediumThe burning of fossil fuels for transportation (cars, planes, ships) and energy production is the main contributor to an individual's or country's carbon footprint. A carbon footprint is the total amount of greenhouse gases generated by our actions.
Eating a diet with less meat can significantly lower your carbon footprint, as livestock farming produces more greenhouse gases than all the world's transport combined!