Chemistry is the study of matter, which includes everything around us and the stuff that our bodies are made up of. It is the study of elements and compounds, plus how they behave. Gather your test tubes, your scales, your periodic table, and your calculator, and let’s test your knowledge of basic chemistry. If you’re successful, you’ll earn an Au (gold) star!
1: True or false: Cooking food involves chemical reactions.
It’s true—when you cook food, the changes that take place are chemical reactions. Similarly, as your body digests that food, more chemical reactions are happening.
2: How many known elements are there?
As of 2020, scientists have identified 118 elements. An element is a material that can’t be broken down or changed to become another element using chemical reactions. However, a nuclear reaction can change one element into something else.
3: Who sets the names and symbols for elements?
The IUPAC, or International Union of Pure and Applied Chemistry, sets the names and symbols for all elements. These names and symbols are used in scientific literature, but sometimes individual countries recognize other names for common use.
4: How many of the known elements occur naturally on Earth?
Although chemists recognize 118 known elements, only 94 of those occur naturally on Earth. The remaining 24 are synthetic elements.
5: What is the most common element found in the universe?
Hydrogen is the most common element found in the universe. Next is helium, the element that makes our party balloons float.
6: Which of the following is NOT an element?
Brass is not an element because it is made up of copper and zinc. Copper and zinc are elements, as are gold, iron, and uranium.
7: What is the element symbol for silver?
The abbreviation for each element is one or two letters, with the first letter always capitalized. The symbol for silver is Ag, from its Latin name “argentum.” The abbreviations in the periodic table include all letters of the alphabet except J.
8: What is an atomic number?
Each element is identified by the number of protons in its atoms. An element always has the same atomic number, but the number of electrons or neutrons may vary.
9: In the periodic table, elements are arranged in order by what sort of number?
Each element has a unique atomic number. Helium, or He, has an atomic number of 1, so it is in the first column of the first row in the periodic table. Dmitri Mendeleev, a Russian chemist, proposed the first periodic table in 1869.
10: In the periodic table, what are the vertical columns called?
Elements in the same group (or family) share similarities in the electronic configuration of their atoms. As a result, they share certain physical and chemical properties. The periodic table has 18 groups, in 18 columns.
11: What is a period in the periodic table?
A horizontal row of elements in the periodic table is called a period. All elements in the same row have the same number of electron shells.
12: Do you know the chemical formula for salt?
The chemical formula for salt is NaCl. Salt is made up of two elements, Na and Cl, in a 1:1 ratio. Na is the symbol for sodium, and Cl is the symbol for chloride, so salt is sodium chloride.
13: What does the chemical formula H2O represent (with the "2" written as a subscript)?
Water is made up of hydrogen, or H, and oxygen, or O. The subscript 2 after the H tells you that you need two hydrogen atoms for every one oxygen atom. Are you thirsty now?
14: What kind of charge can an atom have?
An atom can be neutral, positive, or negative. If the atom has an equal number of protons and electrons, it has no electrical charge.
15: What is the term for the center of an atom?
The nucleus of an atom contains protons and neutrons, which make up 99% of the mass of an atom. A nucleus is always positively charged. The plural of “nucleus” is “nuclei.”
16: What part of an atom is NOT located in the nucleus?
Electrons are not located in the nucleus of an atom. They are negatively charged, and they move around throughout an atom.
17: One main type of chemical bond between atoms is ionic. Can you name the other main type?
The two main types of chemical bonds are ionic and covalent. In an ionic bond, one atom transfers one or more valence electrons to another atom. In a covalent bond, atoms share electron pairs.
18: What is used to neutralize an acid?
A weak base is used to neutralize an acid. Conversely, a weak acid is used to neutralize a base. A bee sting is acidic, and it can be neutralized with baking powder.
19: Which of the following is a state of matter?
The four states of matter are solid, liquid, gas, and plasma. The state of matter is generally changed by adding or removing energy in the form of heat. Water, for example, can be heated into steam or cooled into ice.
20: Who is known as the father of modern chemistry?
Antoine-Laurent Lavoisier is often called the father of modern chemistry. He discovered the importance of oxygen, both in respiration and in combustion. He also named the element oxygen, from French words that mean “produces acid.”
