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How many protons, neutrons & electrons are present in atom?. Cl. 37. -1. 17. Mass number. 37. -1. Cl. 17. charge. Atomic number. The atomic number gives the protons The mass number gives the (protons + neutrons) The charge give the (protons - electrons).
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How many protons, neutrons & electrons are present in atom? Cl 37 -1 17
Mass number 37 -1 Cl 17 charge Atomic number • The atomic number gives the protons • The mass number gives the (protons + neutrons) • The charge give the (protons - electrons)
From the symbol, the atomic number is 17 37 -1 Cl • Atomic # = Protons • Protons = 17 Atomic number 17
Mass number 37 -1 Cl 17 From the symbol, the mass number is 37 • Mass # = Protons + neutrons • 37 = 17 protons + 20 neutrons
37 -1 Cl 17 charge From the symbol, the charge is (-1) • Charge = protons - electrons • -1 = 17 - electrons • Electrons = 18
Neutrally charged atoms of the same element can have different numbers of which subatomic particle? • Atoms of the same element always have the same number of protons (protons define the element)
Neutrally charged atoms of the same element can have different numbers of which subatomic particle? • Neutral atoms have the same number of electrons as protons.
Neutrally charged atoms of the same element can have different numbers of which subatomic particle? • Neutral atoms of the same element can have a different number of neutrons. The neutrons do not affect the charge or the identity of the atom. They do affect the mass.
Atoms of the same element (therefore having the same number of protons) with a different number of neutrons are called ISOTOPES. Isotopes can be differentiated by their different mass numbers in the element symbol. 12C 13C Carbon-12 Carbon-13
What is the difference between mass number and average atomic mass? • The mass number is the sum of the subatomic particles in the nucleus for one specific isotope of an element.
What is the difference between mass number and average atomic mass? • The average atomic mass takes into account the actual mass of all the isotopes of that element. • The average atomic mass is calculated by finding the weighted average of the masses of all the isotopes of that element.
Atoms of two different elements combined to form a new “unit” are called a COMPOUND. Table salt is a compound. To write the “compound name” for table salt, the symbols for the elements are joined together to show the composition of the molecule. Sodium NaCl Chlorine
Subscripts are used to show how many of each type of atom there are. No subscript = 1 atom Calcium Calcium chloride is used to de-ice roads. CaCl2 Chlorine Subscript = 2 atoms
Usually, the most metallic element (closest to the far left column on the periodic table) is written first. CaCl2 not Cl2Ca
An Ion is formed when the numbers of which two subatomic particles are not equal? • Ions are atoms that have a net charge. Atoms are made of three subatomic particles: protons, neutrons and electrons. • Neutrons do not affect the overall charge. • Answer: Protons (+) & Electrons (-)
An Anion (an’ ion) is an atom with a negative charge (less protons than electrons) A Cation (cat’ eye on) is an atom with a positive charge (more protons than electrons) What is a Cation? Anion? Na+ Cl-
A cation is named using the name of the parent atom Na+ is called the sodium ion or sodium cation Mg 2+ is called the magnesium ion or magnesium cation Naming Cations
Names are obtained by adding -ide to the root of the atom name. Fluorine F + e- fluoride ion Bromine Br e- bromide ion Oxygen O + e- oxide ion Naming Anions