Chemistry Test (Revision) Flashcards
What is chemistry?
The study of matter and its composition, it seeks to expand the understanding of matter and its properties. (Energy is a property of matter)
Characteristics of matter:
- Made up of particles (atoms, molecules, or ions)
- Particles are in constant motion
- Has a mass
- Occupies a volume in space
What is matter?
Any substance that occupies a space and has a mass.
What is a pure substance?
A pure substance has a definite and uniform chemical composition.
What is an element?
A substance composed from one atom.
What is a compound?
Is composed from two or more kinds of atoms in a fixed ratio.
What is a mixture?
A combination of two or more pure substances that retain (keep) their individual properties.
What is a homogenous mixture?
Has uniform composition and properties throughout.
What is a heterogenous mixture?
Has a non-uniform composition and varying properties
Physical change:
Matter changes form but not chemical identity.
Chemical change:
A chemical reaction occurs and new products are formed.
What is an electrons’ relative charge?
-1
What is a protons’ relative charge?
+1
What is a neutrons’ relative charge?
0
Location of electron:
Outside nucleus
Electron cloud
Location of proton:
Nucleus
Location of neutron:
Nucleus
What is the relative mass of an electron?
0
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What are isotopes?
Isotopes are the same element with different number of neutrons (same atomic number but different atomic mass).
What is a relative mass?
The weighted average of all the isotopes of an element.
What are valence electrons?
Valence electrons are the electrons in the outermost shell or energy level of an atom (the remaining electrons are known as core electrons).
What is simple distillation used to separate?
A solvent from solution (sugar/salt and water for example)
What is fractional distillation used to separate?
Used to separate a mixture of all liquids (alcohol and water for example)
What is filtration used to separate?
Solids from liquids using filter paper (sand and water for example)
What is crystallization used to separate?
A solid from its liquid solution in the form of pure crystals (sugar/salt in water for example)
What is chromatography used to separate?
Mixtures of soluble substances that are often colored
