chemistry grade 9

What is an atom?

The basic unit of a chemical element, consisting of a nucleus surrounded by electrons.

What is an ion?

An atom or molecule that has gained or lost one or more electrons, giving it a positive or negative charge.

How do ions form?

Ions form when atoms gain or lose electrons to achieve a full outer shell of electrons.

What is an isotope?

Atoms of the same element that have the same number of protons but different numbers of neutrons.

How do you tell how many subatomic particles are in an atom?

The atomic number indicates the number of protons, while the mass number indicates the total number of protons and neutrons.

What information can you get from the periodic table?

You can find the atomic number, atomic mass, element symbol, and information about the properties and classifications of elements.

What is the difference between metals and nonmetals?

Metals are typically malleable, ductile, and good conductors of heat and electricity, while nonmetals are usually brittle and poor conductors.

How do you draw a Bohr-Rutherford diagram?

Start with a nucleus containing protons and neutrons, then draw electron shells around the nucleus representing the arrangement of electrons.

What are physical properties?

Characteristics of a substance that can be observed without changing its identity, such as color, density, and melting point.

What are chemical properties?

Characteristics that describe a substance's potential to undergo chemical changes, such as reactivity and flammability.

What are the classifications of matter?

Matter can be classified into elements, compounds, mixtures, homogeneous mixtures, and heterogeneous mixtures.

Element vs Compound

An element is a pure substance that cannot be broken down, while a compound consists of two or more elements chemically combined.

Homogeneous vs Heterogeneous

Homogeneous mixtures have a uniform composition, while heterogeneous mixtures consist of visibly different substances.

Pure substances vs Mixtures

Pure substances have a fixed composition and distinct properties, while mixtures consist of two or more substances combined physically.

What is a physical change?

A change that affects one or more physical properties of a substance without altering its chemical composition.

What is a chemical change?

A transformation that alters the chemical composition of a substance, resulting in the formation of new substances.

What are the signs of a chemical change?

Signs include color change, gas production, formation of a precipitate, or temperature change.

What is density?

Density is the mass per unit volume of a substance, often expressed in grams per cubic centimeter (g/cm³).

How do you solve for density?

Density can be calculated by dividing the mass of a substance by its volume (Density = Mass/Volume).

How do you solve for mass?

Mass can be calculated by multiplying density by volume (Mass = Density x Volume).

How do you solve for volume?

Volume can be calculated by dividing mass by density (Volume = Mass/Density).

What is solubility?

The ability of a substance to dissolve in a solvent at a given temperature and pressure.

How does temperature affect solubility?

In most cases, increasing temperature increases the solubility of solids in liquids but decreases the solubility of gases.

What is reactivity?

Reactivity refers to how readily a substance undergoes a chemical reaction with other substances.

How can you predict reactivity from the periodic table?

Reactivity can often be predicted based on an element's position in the periodic table, with groups indicating similar chemical behavior.

How do valence electrons influence reactivity?

The number of valence electrons determines how easily an atom can form bonds and therefore its reactivity with other elements.