Unit 1-3 Flashcards
What is a mixture?
In chemistry, a mixture is a material made up of two or more different substances which are physically combined. A mixture is the physical combination of two or more substances in which the identities are retained.
What is a homogeneous mixture?
Homogeneous mixtures have the same composition throughout, and the individual parts of the mixture are not easily identifiable. While we normally think of solutions as liquids, such as soft drinks and lemonade, they can actually be in the form of solids, liquids, and gases. Homogeneous mixtures can also be a combination of these forms, as in a liquid-gas mixture.
What is a heterogeneous mixture?
In a heterogeneous mixture, the substances do not blend smoothly throughout, and the individual substances that compose the mixture can be detected. Heterogeneous mixtures can typically be separated back into their individual components through chemical or physical means.
What is a pure substance?
A pure substance or chemical substance is a material that has a constant composition (is homogeneous) and has consistent properties throughout the sample. A pure substance participates in a chemical reaction to form predictable products. In chemistry, a pure substance consists only of one type of atom, molecule, or compound.
What is an impure substance?
Impure substances may be mixtures of elements, mixtures of compounds, or mixtures of elements and compounds.
What is a compound?
Chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements.
Ex. Methane, in which four hydrogen atoms are bound to a single carbon atom, is an example of a basic chemical compound.
What is an element?
A chemical element is a species of atom having the same number of protons in their atomic nuclei. For example, the atomic number of oxygen is 8, so the element oxygen describes all atoms which have 8 protons.
What is matter?
Anything that has mass and takes up volume.
What is mass? What is it not?
A measure of the total quantity of matter in an object. IT IS NOT WEIGHT
What is volume?
A measure of the total space occupied by an object.
What is density?
A ratio of the mass of an object to the volume occupied by that object.
Density= mass/volume
- if the mass increases, so does the density* = proportional relationship (up and up)
- if the volume decreases, the density gets larger* = inverse relationship (up and down)
What are the two types of observations?
Quantitative: involving measurement that can be written down with numbers (ex. Hairs on your head)
Qualitative: not involving measurement (ex. Hair color)
Density = X/X
Mass/ Volume
Density usually _____ with increasing temperatures.
Decreases
Density is _____ proportional to mass.
Directly
Density is _____ proportional to volume.
Inversely
Can an element be broken down into simpler substances in any way?
No
What is an atom?
It is the smallest particle that can exist and still have the properties of the element.