atoms, elements, compounds, and mixtures Flashcards
what are atoms?
the smallest units of matter that have the properties of a chemical element
What kind of property is a charge?
A physical property
Charges allow particles to ________
move through or remain still in an electromagnetic field
What is an electromagnetic field?
Electromagnetic fields are a combination of invisible electric and magnetic fields of force.
What is the charge of an electron?
negative
What is the charge of a proton?
positive
What is the charge of a neutron?
neutral
What particles are in the nucleus?
Protons and neutrons
The nucleus has an overall ____ charge. Why?
positive
because neutrons have no charge and protons have a positive charge, so together they make a positive charge
Electrons occupy _____ at certain ____.
clouds
energy levels/shells
What is an electron cloud?
The general area where an electron may be found. The shell is used for visualization but the cloud is more accurate.
When is an atom neutral?
When it has the same number of protons and electrons
When is an atom positive?
When it has more protons than electrons (has lost electrons)
When is an atom negative?
When it has more electrons than protons (has gained electrons)
What is a pure substance?
a substance made up of only one type of atom/molecule (ie an element or compound). Can be either an element or compound (molecule with different elements in distinct ratios)
What is a molecule?
Two or more atoms chemically combined. Atoms can be the same or different. All compounds are molecules, not all molecules are compounds.
What is a compound?
A molecule with at least two different elements in a fixed ratio
What is a chemical substance?
Something that can’t be physically separated into different substances (ie diamonds)
Because a compound is reacted chemically, the individual parts no longer ______
have their individual properties
Are the parts of a compound always in a fixed ratio?
Yes
What is a mixture?
A mix of two or more different substances that aren’t in a fixed ratio (ie salad). The substances are only physically combined and can be separated
What are the two types of mixtures
Heterogeneous and homogeneous
What is a heterogeneous mixture?
A mixture that doesn’t look the same all throughout. Different parts of it look different and aren’t the same. Can be separated physically
What is a homogeneous mixture?
Looks the same throughout. Cannot be separated physically
What is filtration?
The act of removing a solid that is not soluble (doesn’t dissolve) from a liquid by pouring the solution with the solid and the liquid through filter paper. Solid collects on paper. a way to separate a mixture
What is chromatography?
used to test whether a liquid is a substance or a mixture by putting a dot of something on a layer of silica on a plate and placing it in the solvent (part doing the dissolving(liquid phase), and watching it slowly move up the plate(solid-state). doesn’t test the whole substance
What is evaporation as a separation process?
Separates a solvent liquid from a soluble solid by vaporizing the liquid and leaving the solid behind
What is a solvent?
The substance that is doing the dissolving in a solution
What is a solute?
The substance that is being dissolved in the solvent
What is extraction?
removing one compound from another by putting the mixture with a solution where the substance that is wanted is soluble but the other substances aren’t (so only the soluble one is in the solution)
What is distillation?
Purifying a liquid by heating a mixture of liquids where the liquids have different boiling points and so when the mixture is put under heat, one evaporates first and is transferred to a different container to be cooled.
