unit 2 topic 1-3 Flashcards
chemistry
a branch of science that deals with the composition and properties of substance and various forms of matter.
caustic
capable of burning, corroding or destroying living tissue.
Homogenous
when the particles in a mixture are uniformly scattered
Heterogenous
when the particles in a mixture are NOT uniformly scattered.
Physical change
occurs when a substance changes form, but NOT chemical composition
chemical change
occurs when one or more NEW. substances are formed from a chemical reaction
Law of conservation of mass
in a chemical change, the total mass of the new substance is always the same as the total mass of the original substances.
Law of definite composition
compounds are pure substances that contain two or more elements combined together in fixed proportions
electrolysis
the process of decomposing a chemical compound by passing an electric current through it
element
a pure substance made up of only one type of particle
compounds
a pure substance made up of two or more elements chemically combined together
electrons
negatively charged particles
atomic nucleus
the centre of the atom contains the protons and neutrons.
proton
positively charged particles
neutrons
neutral ( uncharged) particles
the particle model of matter
- all matter is made up of extremely tiny particles
- each pure substance has its own kind of particle, different from the particles of other pure substances.
- particles attract each other.
- particles are always moving
- particles at a higher temperature move faster on average than particles at a lower temperature
matter
anything that has a mass and takes up space
mixture
is a substance made by combining two or more different materials together
solutions
a homogenous mixture of two or more substances
suspensions
a heterogeneous mixture in which particles settle slowly after mixing
colloid
a heterogenous mixture composed of fine particles evenly distributed throughout a second substance
what is emulsions
types of colloids in which liquids are dispersed in liquids
quantitative physical properties
a characteristic of a substance that can be measured numerically (a quantity)
qualitative physical properties
a characteristic of a substance that can be described but not measured numerically
density
amount of matter that occupies a certain space; the mass per unit volume of a substance
combustibility
is a measure of how easily a substance bursts into flame, through fire fire or combustion.
melting point
the temperature at which a solid changes to a gas
what is a boiling point
the temperature at which a water turns into a gas
what is precipitate
is a solid that forms as the result of a chemical reaction or leftovers
daltons atomic theory
states that all mater is made up of small particles called atoms. Atoms cannot be created, destroyed, or divided into small particles.
what is one thing that Daltons atomic theory states
all atoms of the same element are identical in mass and size.
Atoms in one element are different in mass and size form atoms of another element.
what does Daltons theory state about compounds
they are created when atoms of different elements link together in definite proportions
what is Thomson’s plum pudding atomic model
he discovered that atoms are composite objects made of pieces with positive and negative charge and that the negatively charged elections within the atom were very small compared to the entire atom.
Rutherford solar system atomic model
he said that the positive charges and mass of the atom are concentrated in the centre of the atom or nucleus
2. negatively charges particles moving rapidly around the nucleus
what is the bohr’s atomic model state
electrons are arranged in definite energy levels
- elections follow a prescribed orbit around the nucleus
- electrons may be dislodged from orbits (energy levels) when they absorb or release energy
what is the election cloud mode l
- electrons has a wave-like properties
- electrons exist in definite exist in definite energy levels
- location of the electron is uncertain, it is described in terms of the probability of being fed in a cartoon region of space around the nucleus
- these regions of space are called orbitals.
what is the Billiard Ball model
- smallest particle of mater (Atom)
- for a given substance atoms are identical in size, shape and mass
- smallest part of an element that can take part in chemical change and combine in whole numbers.
- atom is indivisible, unchangeable and indestructible
