Chemical reactions Flashcards
What is an aqueous solution
A mixture in which a substance is dissolved in water
If a substance is in an aqueous solution, it is represented using the symbol (aq).
What is an atom
The smallest particle of an element
An atom is made up of even smaller subatomic particles –** protons, neutrons and electrons**.
What is a balanced equation
An equation with **equal numbers **of atoms of each element on either side
A balanced chemical equation follows the law of conservation of matter.
What is a chemical bond
An attractive force that holds atoms together
A chemical bond can hold atoms together in a molecule or lattice.
What is a chemical equation
A representation of how a chemical reaction rearranges atoms
A chemical equation can be represented in words, symbols, or diagrams.
What is a chemical formula
A symbol that shows the chemical composition of a molecule or lattice
The chemical formula for water is H2O as each molecule has two hydrogen atoms and one oxygen atom.
What is a **chemical reaction **?
The re-arrangement of atoms to form one or more new substances
In a chemical reaction the number of each type of atom remains the same.
What is a chemical symbol
One or two letters used to represent an element
The first letter of a chemical symbol is uppercase and the second letter is lowercase.
What is a coeffiecient
A number placed before a formula in a chemical equation
A** coefficient** is placed before a formula, whereas a subscript is used within it.
What is a compound
Two or more elements joined together by chemical bonds
The compound sodium chloride consists of sodium and chloride atoms chemically bonded together.
What is an element
A substance made up of only one type of atom
Gold is an element in which every atom has 79 protons.
What is the Law of conservation of matter
The rule that the **number **of atoms in a chemical reaction remains the same
During all chemical reactions, the total number of atoms of each element doesn’t change.
What is a molecule
A group of atoms bonded together
An oxygen gas molecule is made up of two oxygen atoms bonded together.
What is the periodic table
The organisation of chemical elements in order of atomic number
The periodic table arranges elements with similar properties in the same group (column).
What is a **physical **change
A change in matter that does not form new substances
Physical changes include breaking, mixing and changing the state of a substance.
What is a product
A substance formed by a chemical reaction
In a chemical equation, the products are located to the right of the arrow.
What is a reactant
A substance that reacts to form one or more new substances
In a chemical equation, the reactants are located to the left of the arrow.
What does reactive mean
Tending to** take part** in chemical reactions
Sodium is one of the most reactive elements in the periodic table.
A state symbol is used
A symbol used to indicate the state of matter of a substance
The state symbol (s) is used for solids, (l) for liquids, (g) for gases, or (aq) for aqueous solutions.
What is a structural equation
A type of equation that shows how the atoms are rearranged
Structural equations can use ball-and-stick models to show how atoms rearrange.
What is a subscript
A number used to show how many atoms of an element are present
The subscript 2 in H2O shows there are 2 hydrogen atoms present in water.
Symbol equation
A chemical equation that uses chemical formulas to represent substances
A symbol equation would represent ammonium as the chemical formula NH₃.
What is an unbalanced formula
An equation with an **unequal **number of atoms on either side
**Unbalanced **equations must be balanced so that they follow the law of conservation of matter.
What is a word equation
A chemical equation that** uses names** to represent substances
A word equation would represent ammonium in an equation as the word ammonium.
