Chemical Reactions and Compound Formulae

True (A)

products

<p>products</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>There are two hydrogen atoms. (C)</p> Signup and view all the answers

<p>The variable and the unit</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>zero</p> Signup and view all the answers

<p>18</p> Signup and view all the answers

<p>2, 6</p> Signup and view all the answers

<p>Y-axis = The vertical axis showing one variable Scale = Determines the increment of values on the axes Data points = The plotted observations on the graph X-axis = The horizontal axis showing the other variable</p> Signup and view all the answers

<p>H2O = Water Mg(OH)2 = Magnesium Hydroxide C2H6 = Ethane NaCl = Sodium Chloride</p> Signup and view all the answers

<p>10 (A)</p> Signup and view all the answers

<p>6 (C)</p> Signup and view all the answers

<p>To represent the trend of the data</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>4</p> Signup and view all the answers

A chemical reaction is a process where substances interact to form new substances. For example, A + B --> C + D, where A and B are reactants and react to form products C and D.

A chemical change happens when a chemical reaction creates new substances. Examples include burning wood, rusting metal, or cooking food.

A physical change occurs when no new substances are formed. This includes changes in state like freezing, melting, or boiling, as well as cutting, bending, or dissolving.

The substances that react in a chemical reaction are called reactants. They are on the left side of the arrow.

The substances that are formed in a chemical reaction are called products. They are on the right side of the arrow.

A graph that shows the relationship between two variables, often using data points plotted on a grid.

The line on a scatter graph that shows the general trend of the data points.

A unit of measurement for a physical quantity, such as grams, centimeters, or degrees Celsius.

A method of representing data visually using points on a grid to show the relationship between two variables.

A scale where the numbers on the axis increase by a constant factor (like 10, 100, or 1000).

A method of calculating the relative molecular mass (Mr) of a compound. You add up the atomic masses of all atoms in the molecule.

The point on a graph where the x-axis and y-axis intersect.

A subscript number following an element symbol indicates the number of atoms of that element in a molecule. For example, H2O indicates two hydrogen atoms and one oxygen atom.

A coefficient placed before a chemical formula represents the number of molecules of that compound. For instance, 2H2O denotes two molecules of water.

Brackets in a chemical formula enclose a group of atoms that act as a unit. The number outside the bracket multiplies all elements within the bracket. For example, Mg(OH)2 indicates one magnesium atom, two oxygen atoms, and two hydrogen atoms.

The relative formula mass (Mr) of a compound is the sum of the atomic masses of all atoms present in the formula. It is calculated by multiplying the atomic mass of each element by its subscript and adding the results. For example, the Mr of H2O is (2 x 1) + (1 x 16) = 18.

A chemical formula represents the composition of a compound by using element symbols and subscripts to indicate the number of atoms of each element. For example, H2O represents one molecule of water, consisting of two hydrogen atoms and one oxygen atom.

Different subscripts and coefficients in a formula indicate different proportions of elements and molecules in a chemical compound. This is essential because it reveals the exact arrangement of atoms within each molecule.

By examining the subscripts and coefficients in a chemical formula, we can determine the number of atoms of each element present in a particular molecule. This information is crucial for understanding the properties and behavior of the compound.

A chemical structure is a diagram that visually represents the arrangement of atoms in a molecule. It shows the bonds between atoms and their spatial orientation. This information is crucial for understanding how the molecule functions and interacts with others.