Glossary Flashcards
Chemistry
Study of elements and the compounds tehy form, and the reactions they undergo
Matter/ Material
Gas, liquid, or solid.
Anything that has MASS / VOLUME
Properties
Characteristics that give matter its unique identity
Extensive Prop
A property that depends on the AMOUNT of the material in a sample such as MASS/ VOLUME
Intensive prop
A property that is INDEPENDENT of the amount of the material in a sample such as DENSITY / COLOR
Physical properties
properties that can be measured without changing the composition of a substance such as COLOR/ MELTING PT
Chemical properties
properties that describe the composition and reactivity of a substance
i.e HOW IT CHANGES INTO OTHER SUBSTANCES
Substance/ component
A single, distinct chemical species
i.e PURE MATERIAL, such as water and oxygen.
It has a composition that remains unchanged
States of matter
the 3 forms in which matter cna be found ; solid, liquid/ gas
Change of States
Transformations of matter from one state to another, such as from a liquid to a gas.
eg Boiling water= produces steam
Mixture
Combination of 2 or more substances in which each substance retains its own chemical identity
Element
A substance that cannot be separated into more simple substances by chemical . physical means such as Oxygen
Compound
A substance composed of 2/ more elements combined chemically in FIXED PROPORTIONS and are classified as MOLECULAR (water, H2o) and NON MOLECULAR (sodium chloride NaCl)
Homogenous mixture
Composition is uniform throughout.
I.e all mixture have the same INTENSIVE PROPERTIES, eg air/ sea water
Heterogenous mixture
Composition is not uniform.
i.e intensive properties vary from place to place in mixture ( MILK/ ROCKS)
Atom
The smallest unit of matter that retains the properties of an element
Allotropes
Diff forms of the same element
i. e the FORMS have their atoms arranged differently .
eg. graphite and diamond = allotropes of carbon
Chemical formula
Notation for a chemical COMPOUND using the chemical symbols for the elements presnet
eg. water - H2O b/c both elements hydrogen and oxygen are chemically combined in teh ratio of 2 hydrogens and one oxygen.
Molecular Formula
A chemical formula that indicates the actual number of atoms of each element in one molecule OF a substance
Empirical formula
A chemical formula that indicates the actual number of atoms and their relative numbers in a substance in the smallest possible WHOLE NUMBER RATIO
eg. Hydrogen Peroxide= MF H2O2, EF= HO
Ethylene= MF= C2H4, EF= CH2
Subatomic particles
The central core of an atom that contains protons and neutrons
Protons (p)
A positively charged subatomic particles present in the nucleus of an atom
Electron (e)
A negatively charged subatomic particle present far outside the nucleus of an atom.
It has a mass 1/1836 times that of a proton
Neutron
An electrically neutral particle present in the nucleus of teh atom.
Has approx. the same mass as a proton.
Diff numbers of neutrons in the nuclei of an element from isotopes of that element.
Atomis Mass Units (MU)
A unit based on the value of 12 amu for the mass of the isotope of carbon (12C) that has 6 protons and 6 neutrons in the nucleus.
Thus a proton and neutron have almost the same mass of 1 amu each, and an electron has a mass of 0.0005 amu
Atomic number (Z)
The number of protons in the nucleus of an atom of an element.
This number identifies a particular element for example Z= 30 must be zinc
Mass Number (A)
The sum of the number of protons and neutrons in the nucleus of an atom of a particular isotope of an element.
Atomic Symbol
Defines atom completely by utilising the chemical symbol X, of an element combine with A, Z
eg..A/Z X
Periodic table
The arrangement of the elements in the order of increasing atomic number with elements having similar properties placed in vertical columns
Metals
Represet 4/5 of the elements in teh PT, and are solids at room temp(expt mercury)
Metals have LUSTER, MELLEABILITY, DUCTILITY and good THERMAL and ELECTRICAL CONDUCTIVITY.
eg. Sn. Fe, Zn
Non metals
Represent 1/5 of teh elements in the PT and teh majority 2/3 are gaseous and the remaining 1/3 are solids (METTALOIDS)
Most of these elemenst are POOR CONDUCTORS of heat & electricity. H/w Metalloids or semiconductors have properties intermediate btw those of metals an non metals
Inert gases
composed of the 6 elements; He, Ne, Ar, Kr. Xe, Rn and occupy the last column of the PT.
All these elements are very nonreactive , all are gases at room temp and exist as individual atoms
Molecules
2/ more atoms held together by chemical bonds.
All the remaining nonmetals ,
1.e not including metalloids and the inert gases, exist as molecules.
eg. N2 , O2, Cl2, P4, S8
Ion
An electrically charged atom or group of atoms (polyatomic ions)
Ions can be positively/ negatively charged depending on whether electrons are lost (positive) / gained (negative
) by the atoms
cation
An ion with a positive charge, formed by the loss of one or more electrons; such as Na+, Ca+, NH+4
Anion
A negatively charged ion formed by the gain of one or more electrons; sucj as Cl0, O2-, No -3
