Unit 1 Flashcards
Chemical change
When the chemical composition of a substance is altered and results in new substances being formed
Chemical reaction
The conversion of two or more elements to a chemical compund
Compound
Contains two or more elements and has chemical and physical properties that are usually different from those of the elements of which it is composed.
Distillation
Physical process of converting homogenous mixtures
The mixture is boiled, and the most volatile substance is boiled first, and then it is condensed back into a liquid in the recieving flask, while the less volatile component remains in the distillation flask
Electrolysis
Process of using electricity to separate water into hydrogen and oxygen
Elements
substance that cannot be broken down into simpler ones by chemical changes
Experiments
Systematic observations or measurments, usually under controlled conditions in which a single variable changes.
Enables scientist to determine whether the hypothesis is valid, incorrect or must be modified
Filtration
Method of separating heterogenous mixtures, where the mixture is passed through barrier, with holes or pores smaller than the solid particles.
Gases characteristics
Have neither fixed shapes or volumes and expand to fill their container
Heterogenous mixtures
When composition of a material is not completely uniform, or their component parts cannot be easily separated.
Homogenous (or solutions)
Materials that are in the same state, have no visible boundries, and are uniform throughout.
Ex. air and tap water
How are homogenous mixtures separated?
Through physical processes called distillation and crystallization
How can kinetic energy of a substance be changed?
Through heating and cooling, which can change the physical state of a substance
Hypothesis
Educated guess that puts scientist’s understanding of the topic into a form that can be tested
Intermolecular forces
Attractive forces that try to draw particles in
John Dalton’s atomic theory
Fundamental concept that states all elements are composed of atoms
Postulates of the theory was
1. All matter is composed of extremely small particles called atoms.
2. Atoms of a given element are identical in size, mass, and other properties.
3. Atoms of different elements differ in size, mass, and other properties.
4. Atoms cannot be subdivided, created, or destroyed.
5. Atoms of different elements can combine in simple whole number ratios to form chemical compounds.
6. In chemical reactions, atoms are combined, separated, or rearranged.
Kinetic energy
Function of substance temperature that keeps molecules apart and moving around
Law
Verbal or mathematical description of phenomenon that says what happens but not why it happens
Allows for general predictions
Law of Conservation
States that in a chemical reaction, matter is neither created, nor destroyed but remains constant in the system
Total mass of reactants = Total mass of products
Law of definite proportions
a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation.
Applies when elements are reacted together to form the same product, thus can be used to compare to experiments where elements react to form the same compound.
Laws of chemical combination
Foundational laws that describe how substances react
- Law of Conservation of Mass
- Law of Definite Proportions
- Law of Multiple Proportions
Liquid characteristics
have fixed volumes but flow to assume the shape of their containers
Physical change
Process of matter changing from one physical state to another
Pressure
Amount of force exerted on a given area
