How can matter be classified based on its composition, and what distinguishes elements, compounds, and mixtures?
Matter is classified as elements, compounds, or mixtures based on its composition. Elements consist of a single type of atom and cannot be separated into simpler substances. Compounds are pure substances made of two or more different elements chemically bonded and can be separated into simpler substances. Mixtures contain two or more elements and/or compounds physically mixed together and can have variable compositions; they are further categorized as homogeneous (uniform composition) or heterogeneous (non-uniform composition).
Compared to pure substances, how are mixtures characterized in terms of composition?
Mixtures are characterized by having variable composition, meaning they consist of two or more substances physically mixed together, unlike pure substances which have a fixed, single composition.
What is the basic functional unit of matter in chemistry?
The atom is the basic functional unit of matter in chemistry.
How do you determine if a substance is a pure substance or a mixture?
You determine this by checking if the substance has a single (pure substance) or variable (mixture) composition.
What distinguishes a homogeneous mixture from a heterogeneous mixture?
A homogeneous mixture has a uniform composition throughout, while a heterogeneous mixture has a non-uniform composition with distinguishable parts.
Give an example of a homogeneous mixture and explain why it fits this category.
Air is a homogeneous mixture because it contains various gases mixed together but appears uniform throughout.
Why is O2 considered an element even though it contains two atoms?
O2 is considered an element because it is made up of only one kind of atom, oxygen, even though there are two atoms bonded together.
What question do you ask to determine if a pure substance is an element or a compound?
You ask if the pure substance can be separated into simpler substances; if not, it's an element, if yes, it's a compound.
What is a common example of a heterogeneous mixture and why?
Oil and water is a common example because the two substances do not mix uniformly and can be seen as separate layers.
What is the key characteristic of compounds that differentiates them from mixtures?
Compounds have elements chemically bonded together in fixed ratios, while mixtures involve physical mixing without chemical bonding.