Matter Classification
What is an element?
A substance that cannot be broken down into simpler substances by chemical means.
How many elements are in the periodic table?
As of 2023, there are 118 confirmed elements.
What is cohesion?
The tendency of molecules of the same substance to stick together.
What is the pH scale?
A scale that measures the acidity or basicity of a solution.
What does conservation of mass mean?
The principle stating that mass is neither created nor destroyed in a chemical reaction.
What is a compound?
A substance formed when two or more elements chemically bond together.
What is the atomic number?
The number of protons in the nucleus of an atom, which defines the element.
What is adhesion?
The tendency of molecules of different substances to stick together.
Compare an acid and a base.
Acids donate protons (H+) when dissolved in water, while bases accept protons.
Describe a chemical reaction where mass stays the same.
The reaction of hydrogen and oxygen to form water, where the total mass of reactants equals the total mass of products.
What is a homogeneous mixture?
A mixture that has a uniform composition throughout.
How do you find the mass of an atom on the periodic table?
By referring to the atomic mass listed for each element, which is usually an average of the isotopes.
What is surface tension in water?
The cohesive force at the surface of water that allows it to resist external force.
What happens when an acid and a base mix?
They undergo a neutralization reaction, producing water and a salt.
How can you show conservation of mass in a chemical equation?
By ensuring that the number of atoms of each element is the same on both sides of the equation.
What makes a heterogeneous mixture different?
It contains distinct substances or phases that can be visibly distinguished.
What do valence electrons do in chemical reactions?
They are involved in forming bonds with other atoms, determining the chemical reactivity of the element.
How does cohesion affect water droplets?
It causes water droplets to form beads on surfaces due to the attraction between water molecules.
What is a strong acid and a weak acid?
A strong acid completely ionizes in solution (e.g., hydrochloric acid), while a weak acid only partially ionizes (e.g., acetic acid).
Why is photosynthesis important for mass conservation?
It converts light energy into chemical energy while maintaining the mass of the reactants and products.
Give an example of each type of matter classification.
Element: Oxygen (O), Compound: Water (H2O), Homogeneous mixture: Saltwater, Heterogeneous mixture: Salad.
How can you tell if an element is a metal or a non-metal?
By its position on the periodic table; metals are typically on the left side, while non-metals are on the right side.
Give an example of adhesion in nature.
Water climbing up plant roots and stems through capillary action.
How do you use pH indicators?
They change color in response to the acidity or basicity of a solution, helping to determine its pH level.
Give an example of conservation of mass in a reaction.
The combustion of methane (CH4 + 2O2 → CO2 + 2H2O) where the total mass of reactants equals the total mass of products.