________= given mass of compound /sum of mass numbers of the elements present in a compound.
Mole
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Compound molecules
________ are created when specific proportions of atoms from several elements combine.
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Metals
________ and some other elements, such as carbon, do not have a simple structure but consist of a very large and indefinite number of atoms bonded together.
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An atom consists of a(n) ________ that is surrounded by one or more negatively charged electrons.
central nucleus
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A(n) ________ is a particle of matter that uniquely defines a chemical element.
atom
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helium
Many elements have only one atom per molecule, including ________ (He), argon (Ar), and others.
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constituent particles
Positively charged sodium ions (Na+) and negatively charged chloride ions (Cl)- make up its ________.
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________ can be used to find out how the atoms of an element will combine with the atom (s) of another element to form a chemical compound.
Valency
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chemical reactions
Atoms, the incredibly small building blocks of all matter, take part in ________.
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A negatively charged ion is called ________
anion
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Atomic radius
________ is measured in nanometres.
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Atoms
________ create ions and molecules.
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different elements
A molecule can be created by joining together atoms of the same element or of ________.
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________ are created when atoms join in a ratio of small whole numbers.
Compounds
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A(n) ________ is an association of charged atoms.
polyatomic ion
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The ________ was the most astonishing idea Dalton's atomic theory provided.
atomic mass
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chemical reaction
In a(n) ________, atoms can not be formed or destroyed since they are indivisible particles.
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Eg In a compound such as water, the ratio of the mass of hydrogen to the mass of oxygen is always 1
8, whatever the source of water
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Carbon dioxide (CO2 ) Carbon, Oxygen 3
8
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Ammonia (NH3 ) Nitrogen, Hydrogen 14
3
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Water (H2O) Hydrogen, Oxygen 1
8
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Its formula unit mass can be calculated as
1 × 23 + 1 × 35.5 = 58.5 u
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During a chemical reaction, the sum of the _________ of the reactants and products remain unchanged.
Masses
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Ionic compounds are formed by the combination between ________ an ______.
Metal and non- metals
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Mole is a link between the __________ and __________.
Mass of atoms & number of atoms
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Those ions which are formed from single atoms are called _________.
simple ions
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In a pure chemical compound, elements are always present in a ________ proportion by mass.
definite
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The SI unit of amount of a substance is __________.
mole
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The valency of an ion is _________ to the charge on the ion.
equal
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The abbreviation used for length names of elements are termed as their _______.
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