Science Notes

Key Terms:
4.1
Matter- anything that has mass and occupies space
Pure substance- matter that contains only one kind of particle
Mixture- matter that contains more than one kind of particle
Element- a pure substance that cannot be broken down into simpler parts by chemical methods
Compound- a pure substance made of two or more different elements that are chemically combined

4.2
Physical property- a characteristic of a substance that can be observed and measured without changing the identity of the substance
Viscosity-the measure of a substance’s resistance to flow
Melting point- the temperature at which a solid turns into a liquid
Boiling point- the temperature of which a liquid turns into a gas
Solubility- a measure of the ability of a substance to dissolve in another substance
Density- the ratio of the mass of a substance to the volume it occupies

4.3
Chemical property- the ability of a substance to change (react) and form a new substance
Combustibility- the ability of a substance to burn in air
Stability- the ability of a substance to remain unchanged
Toxicity- the ability of a substance to cause harmful effects in plants and animals

5.1
Atom- the smallest particle of an element that retains the identity of the element
Electron- a negatively charged particle within the atom
Subatomic particle- a particle that is smaller then the atom
Nucleus- in chemistry, the positively charged centre of an atom
Proton- a positive charged particle that is part of every atomic nucleus
Neutron- an unchanged particle that is part of almost every nucleus

5.2
Atomic number- the number of protons in the nucleus of an atom
Mass number- the sum of the number of protons and the number of neutrons in the nucleus of an atom
Isotope- one of two or more forms of an element that have the same number of protons but a different number of neutrons

5.3
Atomic mass- the average mass of the naturally occurring isotopes of an element
Periodic table- a system for organizing the elements into columns and rows, so that elements with similar properties are in the same column
Metal- typically, an element that is hard, shiny, malleable and ductile, and is a good conductor of heat and electricity
Non-metal- typically, an element that is not shiny, malleable, ductile, and is a poor conductor of heat and electricity
Metalloid- an element that shares some properties with metals and some properties with non-metals
Period- a horizontal row of elements in the periodic table
Group- a vertical column of elements in the periodic table

5.4
Valence electron- an electron in the outermost occupied energy level of an atom

6.1
Ion- a positively or negatively charged atom or molecule
Chemical bond- a chemical link between two atoms, which holds the atoms together
Ionic bond- a chemical bond that forms between oppositely charged ions
Ionic compound- a compound made of oppositely charged ions

6.2
Molecular compound- a compound formed when atoms of two or more different element share electrons
Covalent bond- a chemical bond in which one or more pairs of electrons are shared by two atoms
Molecule- the smallest discrete particle of a pure substance, which has one or more shared pair of electrons

Unit 1- Atoms, Elements, and Compounds

• Particle Theory- All mater is made up of tiny particles, each pure substance has its own kind of particle, which is different from the particles of other pure substances, particles attract each other, particles are always moving, particles at higher temperatures move faster , on average, than particles at a lower temperature
• Solids: can’t move freely, close together. Liquids: move freely inside its container. Gases: Moves freely about within its container.
• D=M/V, M=DxV, V=M/D
• Mechanical mixture/heterogeneous= hot chocolate and marshmallows
• Solution/homogenous= tea
• Suspension= something float in it; fine non-settling Particles, flour in water
• Colloid=