Keyterms Chemistry

Question 1

What’s an Ionic Compound?

Answer 1

• A substance formed with cations and anions. Generally, it is formed with
  a (metal) and a (nonmetal) with the metal being a cation and the nonmetal being an anion.

Question 2

What’s an Ion?

Answer 2

A charged atom

Question 3

What’s a Cation?

Answer 3

A positively charged atom (lost electrons)

Question 4

What’s an Anion?

Answer 4

• A negatively charged atom (gained electrons)

Question 5

What’s a Valence Electron?

Answer 5

• Electrons on the last layer of an atom

Question 6

What’s a Binary ionic compound?

Answer 6

• An ionic compound composed of two ions

Question 7

What’s a Polyatomic ion?

Answer 7

• A bond formed between two or more ions

Question 8

What’s a Ternary compound ?

Answer 8

A compound formed between three ions

Question 9

What’s a Molecular compound(covalent compounds)?

Answer 9

• a group of atoms bonded to form a molecule

A molecular compound is made when two or more nonmetals share electrons.

(Examples are water (H₂O) and carbon dioxide (CO₂). These compounds usually have low melting points and don’t conduct electricity.)

Question 10

What’s a Molecule?

Answer 10

• Two or more atoms that form a covalent bond

Question 11

What’s a Binary molecular compound?

Answer 11

(- A Molecular compound formed by two types of atoms)

A binary molecular compound is a compound made of two different nonmetals.

Carbon dioxide (CO₂): Made of carbon and oxygen.

Question 12

What’s a Reactant?

Answer 12

• Substances involved in a chemical reaction

A reactant is a substance that starts a chemical reaction. It changes to form products. For example, in the reaction of water, hydrogen and oxygen are the reactants.

Question 13

What’s a product?

Answer 13

• Substances created as a result of a chemical reaction

Question 14

What’s a chemical equation?

Answer 14

A chemical equation shows what happens in a chemical reaction. It uses symbols to show the starting materials (reactants) and the new substances (products).

For example:

2H₂ + O₂ → 2H₂O

Question 15

What’s a Chemical equation?

Answer 15

A chemical equation is a way of showing a chemical reaction using symbols and formulas. It shows the reactants (starting materials) and products (what’s made) in the reaction.

For example:

H₂ + O₂ → H₂O

Question 16

What’s a Coefficient?

Answer 16

A coefficient is a number placed in front of a chemical formula in a chemical equation to show how many molecules or atoms of a substance are involved in the reaction.

For example, in the equation 2H₂ + O₂ → 2H₂O

the 2 in front of H₂ and H₂O indicates there are two molecules of hydrogen (H₂) and two molecules of water (H₂O) involved.

Question 17

What’s a word equation?

Answer 17

the name of each reactant on one side and the product on the other Hydrogen + oxygen -> water

Question 18

What’s a Skeletal equation?

Answer 18

• Instead of names chemical formulas are used H2+O2 -> H2O

Question 19

What’s Balanced chemical equation?

Answer 19

• Coefficients are added to ensure that the mass is the same 2H2+O2 -> 2H2O

Question 20

What’s the states of substances?

Answer 20

Solid(s), Liquid(l), Gas(g), Aqueous(dissolved in a liquid) solution(aq)

Question 21

What’s Precipitate?

Answer 21

A precipitate is a solid that forms in a liquid when two liquids react.

It’s like when something “falls out” of the liquid.

For example, mixing two clear liquids can make a solid appear at the bottom of the container.

(- a substance that forms as a result of a chemical reaction)

Question 22

What’s a Synthesis reaction?

Answer 22

A synthesis reaction is when two or more simple reactants combine to form a more complex substance. The general formula is:

A + B → AB

For example, when hydrogen gas (H₂) reacts with oxygen gas (O₂), they form water (H₂O):

2H₂ + O₂ → 2H₂O

Here, two simple molecules (hydrogen and oxygen) combine to make a more complex molecule (water).

Question 23

What’s a Decomposition reaction?

Answer 23

A decomposition reaction is when a single compound breaks down into two or more simpler reactants.

The general formula is: AB → A + B

For example, when calcium carbonate (CaCO₃) is heated, it breaks down into calcium oxide (CaO) and carbon dioxide (CO₂):

CaCO₃ → CaO + CO₂

In this case, one compound (calcium carbonate) breaks down into two simpler substances (calcium oxide and carbon dioxide).

Question 24

What’s a Single displacement reaction?

Answer 24

A single displacement reaction is when one element replaces another in a compound.
The general formula is:

A + BC → AC + B

For example, when zinc (Zn) reacts with hydrochloric acid (HCl), zinc replaces hydrogen to form zinc chloride (ZnCl₂) and hydrogen gas (H₂):

Zn + 2HCl → ZnCl₂ + H₂

In this reaction, zinc displaces hydrogen from hydrochloric acid.

Question 25

What’s an Activity series?

Answer 25

An activity series is a list that ranks metals by how reactive they are. The most reactive metals are at the top, and the least reactive are at the bottom. For example, a metal higher in the series can replace a metal lower in the series in a reaction. So, zinc can replace copper in a compound, but copper can't replace zinc. - **Most reactive metals** (like sodium) are at the top. - **Least reactive metals** (like gold) are at the bottom.

Question 26

What’s a Double displacement reaction?

Answer 26

A **double displacement reaction** is when two compounds react, and the positive and negative ions of each compound switch places to form two new compounds. The general formula is: AB + CD → AD + CB For example, when silver nitrate (AgNO₃) reacts with sodium chloride (NaCl), silver chloride (AgCl) forms as a precipitate, and sodium nitrate (NaNO₃) remains in solution: AgNO₃ + NaCl → AgCl (s) + NaNO₃ In this reaction, the silver (Ag⁺) switches with the sodium (Na⁺), and the chloride (Cl⁻) switches with the nitrate (NO₃⁻).

Question 27

What’s a Catalyst?

Answer 27

A catalyst is a substance that speeds up a chemical reaction without being used up. It helps the reaction happen faster but remains unchanged after the reaction. Example: In the breakdown of hydrogen peroxide (H₂O₂), the enzyme **catalase** speeds up the reaction, turning hydrogen peroxide into water (H₂O) and oxygen (O₂), but the catalase isn’t used up: 2H₂O₂ → 2H₂O + O₂ So, catalase helps the reaction go faster but stays the same.

Question 28

What’s Leaching?

Answer 28

**Leaching** is when a liquid is used to dissolve and remove a substance from a solid. For example, in mining, chemicals like cyanide are used to dissolve gold from rocks. In soil, rain can wash away nutrients, which is also a type of leaching.

Question 29

What’s a halo-gen?

Answer 29

A halogen is an element from group 17 of the periodic table. The halogens include: _________________highest Fluorine (F) Chlorine (Cl) Bromine (Br) Iodine (I) Astatine (At) _________________lowest

Question 30

What’s acid?

Answer 30

An **acid** is a substance that releases hydrogen ions (H⁺) when dissolved in water. Acids are usually sour and can turn blue litmus paper red. - Lemon juice (citric acid) - Vinegar (acetic acid) - Hydrochloric acid (found in stomach acid) In simple terms, acids are chemicals that can "donate" hydrogen ions.

Question 31

What’s Binary acid?

Answer 31

A binary acids is an acid made of two elements: hydrogen and one nonmetal (like chlorine or sulfur). Examples: -Hydrochloric acid (HCl)– hydrogen and chlorine. - Hydro sulfuric acid (H₂S)– hydrogen and sulfur. These acids are named with "hydro-" and the nonmetal name ending in "-ic."

Question 32

What is Oxoacid?

Answer 32

An oxoacid is an acid that contains hydrogen, oxygen, and another element (like sulfur or nitrogen). Examples: - Sulfuric acid (H₂SO₄)– hydrogen, oxygen, and sulfur. - Nitric acid (HNO₃)– hydrogen, oxygen, and nitrogen. In oxoacids, the hydrogen is bonded to oxygen, which is then bonded to another element.

Question 33

What’s the Ph scale?

Answer 33

The pH scale measures how acidic or basic (alkaline) a substance is. It ranges from 0 to 14: - pH 7 is neutral (neither acidic nor basic), like pure water. - pH less than 7 indicates an **acid**, with lower numbers being more acidic (e.g., lemon juice, vinegar). - pH greater than 7 indicates a **base** (or alkaline), with higher numbers being more basic (e.g., soap, baking soda). The scale is logarithmic, meaning each step on the scale represents a tenfold difference in acidity or alkalinity.

Question 34

What’s pH indicator?

Answer 34

A pH indicator is a substance that changes color to show whether a solution is acidic, neutral, or basic. Examples: - Litmus paper: Red in acids, blue in bases. - Phenolphthalein: Colourless in acids, pink in bases. - Universal indicator: Shows a range of colors from red (acidic) to purple (basic). Indicators are used to test the pH of a solution.

Question 35

What’s Neutralization?

Answer 35

Neutralization is a reaction between an acid and a base that produces water and a salt, making the solution neutral. Example: When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), it forms water (H₂O) and salt (NaCl): HCl + NaOH → H₂O + NaCl In simple terms, neutralization happens when an acid and a base cancel each other out.

Question 36

What’s Liming?

Answer 36

Here's a simplified version of your points: - Liming: The process of adding calcium carbonate to soil to neutralize acidity. - Example of Neutralization: HCl + NaOH → H₂O + NaCl This shows how an acid (HCl) reacts with a base (NaOH) to form water and salt. - Double Displacement Reaction: Neutralization is also a type of **double displacement reaction**, where two compounds exchange ions to form new compounds. - Examples of Acids in Nature**: - Acid rain: Rain with harmful acidic substances. - Acid spills: Accidental release of acidic chemicals. - Acid cleanup: The process of neutralizing or cleaning up acid spills. This covers the process and examples clearly and simply.